![Andrea Righi](/assets/img/avatar_default.png)
Report per-thread I/O statistics in /proc/pid/task/tid/io and aggregate parent I/O statistics in /proc/pid/io. This approach follows the same model used to account per-process and per-thread CPU times. As a practial application, this allows for example to quickly find the top I/O consumer when a process spawns many child threads that perform the actual I/O work, because the aggregated I/O statistics can always be found in /proc/pid/io. [ Oleg Nesterov points out that we should check that the task is still alive before we iterate over the threads, but also says that we can do that fixup on top of this later. - Linus ] Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrea Righi <righi.andrea@gmail.com> Cc: Matt Heaton <matt@hostmonster.com> Cc: Shailabh Nagar <nagar@watson.ibm.com> Acked-by-with-comments: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1720 lines
41 KiB
C
1720 lines
41 KiB
C
/*
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* linux/kernel/fork.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* 'fork.c' contains the help-routines for the 'fork' system call
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* (see also entry.S and others).
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* Fork is rather simple, once you get the hang of it, but the memory
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* management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
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*/
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/unistd.h>
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/completion.h>
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#include <linux/mnt_namespace.h>
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#include <linux/personality.h>
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#include <linux/mempolicy.h>
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#include <linux/sem.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/iocontext.h>
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#include <linux/key.h>
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#include <linux/binfmts.h>
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#include <linux/mman.h>
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#include <linux/fs.h>
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#include <linux/nsproxy.h>
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#include <linux/capability.h>
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#include <linux/cpu.h>
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#include <linux/cgroup.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/jiffies.h>
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#include <linux/futex.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/rcupdate.h>
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#include <linux/ptrace.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/memcontrol.h>
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#include <linux/profile.h>
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#include <linux/rmap.h>
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#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/freezer.h>
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#include <linux/delayacct.h>
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#include <linux/taskstats_kern.h>
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#include <linux/random.h>
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#include <linux/tty.h>
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#include <linux/proc_fs.h>
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#include <linux/blkdev.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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/*
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* Protected counters by write_lock_irq(&tasklist_lock)
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*/
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unsigned long total_forks; /* Handle normal Linux uptimes. */
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int nr_threads; /* The idle threads do not count.. */
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int max_threads; /* tunable limit on nr_threads */
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DEFINE_PER_CPU(unsigned long, process_counts) = 0;
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__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
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int nr_processes(void)
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{
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int cpu;
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int total = 0;
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for_each_online_cpu(cpu)
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total += per_cpu(process_counts, cpu);
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return total;
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}
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
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# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
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static struct kmem_cache *task_struct_cachep;
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#endif
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#ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
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static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)
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{
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#ifdef CONFIG_DEBUG_STACK_USAGE
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gfp_t mask = GFP_KERNEL | __GFP_ZERO;
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#else
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gfp_t mask = GFP_KERNEL;
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#endif
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return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER);
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}
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static inline void free_thread_info(struct thread_info *ti)
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{
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free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
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}
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#endif
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/* SLAB cache for signal_struct structures (tsk->signal) */
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static struct kmem_cache *signal_cachep;
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/* SLAB cache for sighand_struct structures (tsk->sighand) */
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struct kmem_cache *sighand_cachep;
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/* SLAB cache for files_struct structures (tsk->files) */
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struct kmem_cache *files_cachep;
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/* SLAB cache for fs_struct structures (tsk->fs) */
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struct kmem_cache *fs_cachep;
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/* SLAB cache for vm_area_struct structures */
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struct kmem_cache *vm_area_cachep;
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/* SLAB cache for mm_struct structures (tsk->mm) */
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static struct kmem_cache *mm_cachep;
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void free_task(struct task_struct *tsk)
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{
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prop_local_destroy_single(&tsk->dirties);
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free_thread_info(tsk->stack);
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rt_mutex_debug_task_free(tsk);
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free_task_struct(tsk);
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}
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EXPORT_SYMBOL(free_task);
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void __put_task_struct(struct task_struct *tsk)
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{
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WARN_ON(!tsk->exit_state);
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WARN_ON(atomic_read(&tsk->usage));
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WARN_ON(tsk == current);
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security_task_free(tsk);
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free_uid(tsk->user);
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put_group_info(tsk->group_info);
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delayacct_tsk_free(tsk);
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if (!profile_handoff_task(tsk))
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free_task(tsk);
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}
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/*
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* macro override instead of weak attribute alias, to workaround
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* gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
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*/
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#ifndef arch_task_cache_init
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#define arch_task_cache_init()
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#endif
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void __init fork_init(unsigned long mempages)
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{
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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#ifndef ARCH_MIN_TASKALIGN
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#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
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#endif
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/* create a slab on which task_structs can be allocated */
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task_struct_cachep =
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kmem_cache_create("task_struct", sizeof(struct task_struct),
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ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL);
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#endif
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/* do the arch specific task caches init */
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arch_task_cache_init();
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/*
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* The default maximum number of threads is set to a safe
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* value: the thread structures can take up at most half
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* of memory.
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*/
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max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
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/*
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* we need to allow at least 20 threads to boot a system
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*/
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if(max_threads < 20)
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max_threads = 20;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
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init_task.signal->rlim[RLIMIT_SIGPENDING] =
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init_task.signal->rlim[RLIMIT_NPROC];
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}
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int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
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struct task_struct *src)
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{
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*dst = *src;
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return 0;
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}
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static struct task_struct *dup_task_struct(struct task_struct *orig)
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{
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struct task_struct *tsk;
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struct thread_info *ti;
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int err;
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prepare_to_copy(orig);
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tsk = alloc_task_struct();
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if (!tsk)
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return NULL;
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ti = alloc_thread_info(tsk);
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if (!ti) {
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free_task_struct(tsk);
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return NULL;
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}
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err = arch_dup_task_struct(tsk, orig);
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if (err)
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goto out;
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tsk->stack = ti;
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err = prop_local_init_single(&tsk->dirties);
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if (err)
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goto out;
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setup_thread_stack(tsk, orig);
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#ifdef CONFIG_CC_STACKPROTECTOR
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tsk->stack_canary = get_random_int();
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#endif
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/* One for us, one for whoever does the "release_task()" (usually parent) */
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atomic_set(&tsk->usage,2);
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atomic_set(&tsk->fs_excl, 0);
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#ifdef CONFIG_BLK_DEV_IO_TRACE
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tsk->btrace_seq = 0;
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#endif
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tsk->splice_pipe = NULL;
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return tsk;
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out:
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free_thread_info(ti);
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free_task_struct(tsk);
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return NULL;
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}
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#ifdef CONFIG_MMU
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static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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struct vm_area_struct *mpnt, *tmp, **pprev;
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struct rb_node **rb_link, *rb_parent;
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int retval;
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unsigned long charge;
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struct mempolicy *pol;
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down_write(&oldmm->mmap_sem);
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flush_cache_dup_mm(oldmm);
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/*
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* Not linked in yet - no deadlock potential:
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*/
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down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
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mm->locked_vm = 0;
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mm->mmap = NULL;
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mm->mmap_cache = NULL;
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mm->free_area_cache = oldmm->mmap_base;
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mm->cached_hole_size = ~0UL;
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mm->map_count = 0;
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cpus_clear(mm->cpu_vm_mask);
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mm->mm_rb = RB_ROOT;
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rb_link = &mm->mm_rb.rb_node;
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rb_parent = NULL;
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pprev = &mm->mmap;
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for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
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struct file *file;
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if (mpnt->vm_flags & VM_DONTCOPY) {
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long pages = vma_pages(mpnt);
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mm->total_vm -= pages;
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vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
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-pages);
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continue;
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}
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charge = 0;
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if (mpnt->vm_flags & VM_ACCOUNT) {
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unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
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if (security_vm_enough_memory(len))
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goto fail_nomem;
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charge = len;
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}
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tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
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if (!tmp)
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goto fail_nomem;
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*tmp = *mpnt;
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pol = mpol_dup(vma_policy(mpnt));
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retval = PTR_ERR(pol);
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if (IS_ERR(pol))
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goto fail_nomem_policy;
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vma_set_policy(tmp, pol);
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tmp->vm_flags &= ~VM_LOCKED;
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tmp->vm_mm = mm;
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tmp->vm_next = NULL;
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anon_vma_link(tmp);
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file = tmp->vm_file;
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if (file) {
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struct inode *inode = file->f_path.dentry->d_inode;
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get_file(file);
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if (tmp->vm_flags & VM_DENYWRITE)
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atomic_dec(&inode->i_writecount);
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/* insert tmp into the share list, just after mpnt */
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spin_lock(&file->f_mapping->i_mmap_lock);
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tmp->vm_truncate_count = mpnt->vm_truncate_count;
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flush_dcache_mmap_lock(file->f_mapping);
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vma_prio_tree_add(tmp, mpnt);
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flush_dcache_mmap_unlock(file->f_mapping);
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spin_unlock(&file->f_mapping->i_mmap_lock);
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}
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/*
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* Clear hugetlb-related page reserves for children. This only
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* affects MAP_PRIVATE mappings. Faults generated by the child
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* are not guaranteed to succeed, even if read-only
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*/
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if (is_vm_hugetlb_page(tmp))
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reset_vma_resv_huge_pages(tmp);
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/*
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* Link in the new vma and copy the page table entries.
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*/
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*pprev = tmp;
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pprev = &tmp->vm_next;
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__vma_link_rb(mm, tmp, rb_link, rb_parent);
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rb_link = &tmp->vm_rb.rb_right;
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rb_parent = &tmp->vm_rb;
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mm->map_count++;
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retval = copy_page_range(mm, oldmm, mpnt);
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if (tmp->vm_ops && tmp->vm_ops->open)
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tmp->vm_ops->open(tmp);
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if (retval)
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goto out;
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}
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/* a new mm has just been created */
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arch_dup_mmap(oldmm, mm);
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retval = 0;
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out:
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up_write(&mm->mmap_sem);
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flush_tlb_mm(oldmm);
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up_write(&oldmm->mmap_sem);
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return retval;
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fail_nomem_policy:
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kmem_cache_free(vm_area_cachep, tmp);
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fail_nomem:
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retval = -ENOMEM;
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vm_unacct_memory(charge);
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goto out;
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}
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static inline int mm_alloc_pgd(struct mm_struct * mm)
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{
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mm->pgd = pgd_alloc(mm);
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if (unlikely(!mm->pgd))
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return -ENOMEM;
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return 0;
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}
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static inline void mm_free_pgd(struct mm_struct * mm)
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{
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pgd_free(mm, mm->pgd);
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}
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#else
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#define dup_mmap(mm, oldmm) (0)
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#define mm_alloc_pgd(mm) (0)
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#define mm_free_pgd(mm)
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#endif /* CONFIG_MMU */
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
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#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
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#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
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#include <linux/init_task.h>
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static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
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{
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atomic_set(&mm->mm_users, 1);
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atomic_set(&mm->mm_count, 1);
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init_rwsem(&mm->mmap_sem);
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INIT_LIST_HEAD(&mm->mmlist);
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mm->flags = (current->mm) ? current->mm->flags
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: MMF_DUMP_FILTER_DEFAULT;
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mm->core_state = NULL;
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mm->nr_ptes = 0;
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set_mm_counter(mm, file_rss, 0);
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set_mm_counter(mm, anon_rss, 0);
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spin_lock_init(&mm->page_table_lock);
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rwlock_init(&mm->ioctx_list_lock);
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mm->ioctx_list = NULL;
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mm->free_area_cache = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = ~0UL;
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mm_init_owner(mm, p);
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if (likely(!mm_alloc_pgd(mm))) {
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mm->def_flags = 0;
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return mm;
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}
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|
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free_mm(mm);
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return NULL;
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}
|
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|
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/*
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* Allocate and initialize an mm_struct.
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*/
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struct mm_struct * mm_alloc(void)
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{
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struct mm_struct * mm;
|
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|
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mm = allocate_mm();
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if (mm) {
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memset(mm, 0, sizeof(*mm));
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mm = mm_init(mm, current);
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}
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return mm;
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}
|
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|
|
/*
|
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* Called when the last reference to the mm
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* is dropped: either by a lazy thread or by
|
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* mmput. Free the page directory and the mm.
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*/
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void __mmdrop(struct mm_struct *mm)
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{
|
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BUG_ON(mm == &init_mm);
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mm_free_pgd(mm);
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destroy_context(mm);
|
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free_mm(mm);
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}
|
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EXPORT_SYMBOL_GPL(__mmdrop);
|
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|
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/*
|
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* Decrement the use count and release all resources for an mm.
|
|
*/
|
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void mmput(struct mm_struct *mm)
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{
|
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might_sleep();
|
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|
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if (atomic_dec_and_test(&mm->mm_users)) {
|
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exit_aio(mm);
|
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exit_mmap(mm);
|
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set_mm_exe_file(mm, NULL);
|
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if (!list_empty(&mm->mmlist)) {
|
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spin_lock(&mmlist_lock);
|
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list_del(&mm->mmlist);
|
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spin_unlock(&mmlist_lock);
|
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}
|
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put_swap_token(mm);
|
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mmdrop(mm);
|
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}
|
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}
|
|
EXPORT_SYMBOL_GPL(mmput);
|
|
|
|
/**
|
|
* get_task_mm - acquire a reference to the task's mm
|
|
*
|
|
* Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
|
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* this kernel workthread has transiently adopted a user mm with use_mm,
|
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* to do its AIO) is not set and if so returns a reference to it, after
|
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* bumping up the use count. User must release the mm via mmput()
|
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* after use. Typically used by /proc and ptrace.
|
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*/
|
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struct mm_struct *get_task_mm(struct task_struct *task)
|
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{
|
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struct mm_struct *mm;
|
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|
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task_lock(task);
|
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mm = task->mm;
|
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if (mm) {
|
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if (task->flags & PF_KTHREAD)
|
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mm = NULL;
|
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else
|
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atomic_inc(&mm->mm_users);
|
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}
|
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task_unlock(task);
|
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return mm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_task_mm);
|
|
|
|
/* Please note the differences between mmput and mm_release.
|
|
* mmput is called whenever we stop holding onto a mm_struct,
|
|
* error success whatever.
|
|
*
|
|
* mm_release is called after a mm_struct has been removed
|
|
* from the current process.
|
|
*
|
|
* This difference is important for error handling, when we
|
|
* only half set up a mm_struct for a new process and need to restore
|
|
* the old one. Because we mmput the new mm_struct before
|
|
* restoring the old one. . .
|
|
* Eric Biederman 10 January 1998
|
|
*/
|
|
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
|
{
|
|
struct completion *vfork_done = tsk->vfork_done;
|
|
|
|
/* Get rid of any cached register state */
|
|
deactivate_mm(tsk, mm);
|
|
|
|
/* notify parent sleeping on vfork() */
|
|
if (vfork_done) {
|
|
tsk->vfork_done = NULL;
|
|
complete(vfork_done);
|
|
}
|
|
|
|
/*
|
|
* If we're exiting normally, clear a user-space tid field if
|
|
* requested. We leave this alone when dying by signal, to leave
|
|
* the value intact in a core dump, and to save the unnecessary
|
|
* trouble otherwise. Userland only wants this done for a sys_exit.
|
|
*/
|
|
if (tsk->clear_child_tid
|
|
&& !(tsk->flags & PF_SIGNALED)
|
|
&& atomic_read(&mm->mm_users) > 1) {
|
|
u32 __user * tidptr = tsk->clear_child_tid;
|
|
tsk->clear_child_tid = NULL;
|
|
|
|
/*
|
|
* We don't check the error code - if userspace has
|
|
* not set up a proper pointer then tough luck.
|
|
*/
|
|
put_user(0, tidptr);
|
|
sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new mm structure and copy contents from the
|
|
* mm structure of the passed in task structure.
|
|
*/
|
|
struct mm_struct *dup_mm(struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm = current->mm;
|
|
int err;
|
|
|
|
if (!oldmm)
|
|
return NULL;
|
|
|
|
mm = allocate_mm();
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
memcpy(mm, oldmm, sizeof(*mm));
|
|
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
|
|
if (!mm_init(mm, tsk))
|
|
goto fail_nomem;
|
|
|
|
if (init_new_context(tsk, mm))
|
|
goto fail_nocontext;
|
|
|
|
dup_mm_exe_file(oldmm, mm);
|
|
|
|
err = dup_mmap(mm, oldmm);
|
|
if (err)
|
|
goto free_pt;
|
|
|
|
mm->hiwater_rss = get_mm_rss(mm);
|
|
mm->hiwater_vm = mm->total_vm;
|
|
|
|
return mm;
|
|
|
|
free_pt:
|
|
mmput(mm);
|
|
|
|
fail_nomem:
|
|
return NULL;
|
|
|
|
fail_nocontext:
|
|
/*
|
|
* If init_new_context() failed, we cannot use mmput() to free the mm
|
|
* because it calls destroy_context()
|
|
*/
|
|
mm_free_pgd(mm);
|
|
free_mm(mm);
|
|
return NULL;
|
|
}
|
|
|
|
static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct mm_struct * mm, *oldmm;
|
|
int retval;
|
|
|
|
tsk->min_flt = tsk->maj_flt = 0;
|
|
tsk->nvcsw = tsk->nivcsw = 0;
|
|
|
|
tsk->mm = NULL;
|
|
tsk->active_mm = NULL;
|
|
|
|
/*
|
|
* Are we cloning a kernel thread?
|
|
*
|
|
* We need to steal a active VM for that..
|
|
*/
|
|
oldmm = current->mm;
|
|
if (!oldmm)
|
|
return 0;
|
|
|
|
if (clone_flags & CLONE_VM) {
|
|
atomic_inc(&oldmm->mm_users);
|
|
mm = oldmm;
|
|
goto good_mm;
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
mm = dup_mm(tsk);
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
good_mm:
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
|
|
tsk->mm = mm;
|
|
tsk->active_mm = mm;
|
|
return 0;
|
|
|
|
fail_nomem:
|
|
return retval;
|
|
}
|
|
|
|
static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
|
|
{
|
|
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
|
|
/* We don't need to lock fs - think why ;-) */
|
|
if (fs) {
|
|
atomic_set(&fs->count, 1);
|
|
rwlock_init(&fs->lock);
|
|
fs->umask = old->umask;
|
|
read_lock(&old->lock);
|
|
fs->root = old->root;
|
|
path_get(&old->root);
|
|
fs->pwd = old->pwd;
|
|
path_get(&old->pwd);
|
|
if (old->altroot.dentry) {
|
|
fs->altroot = old->altroot;
|
|
path_get(&old->altroot);
|
|
} else {
|
|
fs->altroot.mnt = NULL;
|
|
fs->altroot.dentry = NULL;
|
|
}
|
|
read_unlock(&old->lock);
|
|
}
|
|
return fs;
|
|
}
|
|
|
|
struct fs_struct *copy_fs_struct(struct fs_struct *old)
|
|
{
|
|
return __copy_fs_struct(old);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(copy_fs_struct);
|
|
|
|
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
if (clone_flags & CLONE_FS) {
|
|
atomic_inc(¤t->fs->count);
|
|
return 0;
|
|
}
|
|
tsk->fs = __copy_fs_struct(current->fs);
|
|
if (!tsk->fs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct files_struct *oldf, *newf;
|
|
int error = 0;
|
|
|
|
/*
|
|
* A background process may not have any files ...
|
|
*/
|
|
oldf = current->files;
|
|
if (!oldf)
|
|
goto out;
|
|
|
|
if (clone_flags & CLONE_FILES) {
|
|
atomic_inc(&oldf->count);
|
|
goto out;
|
|
}
|
|
|
|
newf = dup_fd(oldf, &error);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
tsk->files = newf;
|
|
error = 0;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
#ifdef CONFIG_BLOCK
|
|
struct io_context *ioc = current->io_context;
|
|
|
|
if (!ioc)
|
|
return 0;
|
|
/*
|
|
* Share io context with parent, if CLONE_IO is set
|
|
*/
|
|
if (clone_flags & CLONE_IO) {
|
|
tsk->io_context = ioc_task_link(ioc);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
} else if (ioprio_valid(ioc->ioprio)) {
|
|
tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
|
|
tsk->io_context->ioprio = ioc->ioprio;
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct sighand_struct *sig;
|
|
|
|
if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
|
|
atomic_inc(¤t->sighand->count);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
|
rcu_assign_pointer(tsk->sighand, sig);
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
atomic_set(&sig->count, 1);
|
|
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_sighand(struct sighand_struct *sighand)
|
|
{
|
|
if (atomic_dec_and_test(&sighand->count))
|
|
kmem_cache_free(sighand_cachep, sighand);
|
|
}
|
|
|
|
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig;
|
|
int ret;
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
atomic_inc(¤t->signal->count);
|
|
atomic_inc(¤t->signal->live);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
|
|
tsk->signal = sig;
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
|
|
ret = copy_thread_group_keys(tsk);
|
|
if (ret < 0) {
|
|
kmem_cache_free(signal_cachep, sig);
|
|
return ret;
|
|
}
|
|
|
|
atomic_set(&sig->count, 1);
|
|
atomic_set(&sig->live, 1);
|
|
init_waitqueue_head(&sig->wait_chldexit);
|
|
sig->flags = 0;
|
|
sig->group_exit_code = 0;
|
|
sig->group_exit_task = NULL;
|
|
sig->group_stop_count = 0;
|
|
sig->curr_target = tsk;
|
|
init_sigpending(&sig->shared_pending);
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
sig->it_real_incr.tv64 = 0;
|
|
sig->real_timer.function = it_real_fn;
|
|
|
|
sig->it_virt_expires = cputime_zero;
|
|
sig->it_virt_incr = cputime_zero;
|
|
sig->it_prof_expires = cputime_zero;
|
|
sig->it_prof_incr = cputime_zero;
|
|
|
|
sig->leader = 0; /* session leadership doesn't inherit */
|
|
sig->tty_old_pgrp = NULL;
|
|
|
|
sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
|
|
sig->gtime = cputime_zero;
|
|
sig->cgtime = cputime_zero;
|
|
sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
|
|
sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
|
|
sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
|
|
#ifdef CONFIG_TASK_XACCT
|
|
sig->rchar = sig->wchar = sig->syscr = sig->syscw = 0;
|
|
#endif
|
|
#ifdef CONFIG_TASK_IO_ACCOUNTING
|
|
memset(&sig->ioac, 0, sizeof(sig->ioac));
|
|
#endif
|
|
sig->sum_sched_runtime = 0;
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
taskstats_tgid_init(sig);
|
|
|
|
task_lock(current->group_leader);
|
|
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
|
task_unlock(current->group_leader);
|
|
|
|
if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
|
|
/*
|
|
* New sole thread in the process gets an expiry time
|
|
* of the whole CPU time limit.
|
|
*/
|
|
tsk->it_prof_expires =
|
|
secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
}
|
|
acct_init_pacct(&sig->pacct);
|
|
|
|
tty_audit_fork(sig);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_signal(struct signal_struct *sig)
|
|
{
|
|
exit_thread_group_keys(sig);
|
|
kmem_cache_free(signal_cachep, sig);
|
|
}
|
|
|
|
static void cleanup_signal(struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig = tsk->signal;
|
|
|
|
atomic_dec(&sig->live);
|
|
|
|
if (atomic_dec_and_test(&sig->count))
|
|
__cleanup_signal(sig);
|
|
}
|
|
|
|
static void copy_flags(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
unsigned long new_flags = p->flags;
|
|
|
|
new_flags &= ~PF_SUPERPRIV;
|
|
new_flags |= PF_FORKNOEXEC;
|
|
if (!(clone_flags & CLONE_PTRACE))
|
|
p->ptrace = 0;
|
|
p->flags = new_flags;
|
|
clear_freeze_flag(p);
|
|
}
|
|
|
|
asmlinkage long sys_set_tid_address(int __user *tidptr)
|
|
{
|
|
current->clear_child_tid = tidptr;
|
|
|
|
return task_pid_vnr(current);
|
|
}
|
|
|
|
static void rt_mutex_init_task(struct task_struct *p)
|
|
{
|
|
spin_lock_init(&p->pi_lock);
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
plist_head_init(&p->pi_waiters, &p->pi_lock);
|
|
p->pi_blocked_on = NULL;
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_MM_OWNER
|
|
void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
mm->owner = p;
|
|
}
|
|
#endif /* CONFIG_MM_OWNER */
|
|
|
|
/*
|
|
* This creates a new process as a copy of the old one,
|
|
* but does not actually start it yet.
|
|
*
|
|
* It copies the registers, and all the appropriate
|
|
* parts of the process environment (as per the clone
|
|
* flags). The actual kick-off is left to the caller.
|
|
*/
|
|
static struct task_struct *copy_process(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *child_tidptr,
|
|
struct pid *pid)
|
|
{
|
|
int retval;
|
|
struct task_struct *p;
|
|
int cgroup_callbacks_done = 0;
|
|
|
|
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Thread groups must share signals as well, and detached threads
|
|
* can only be started up within the thread group.
|
|
*/
|
|
if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Shared signal handlers imply shared VM. By way of the above,
|
|
* thread groups also imply shared VM. Blocking this case allows
|
|
* for various simplifications in other code.
|
|
*/
|
|
if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
retval = security_task_create(clone_flags);
|
|
if (retval)
|
|
goto fork_out;
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
rt_mutex_init_task(p);
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
|
|
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
|
#endif
|
|
retval = -EAGAIN;
|
|
if (atomic_read(&p->user->processes) >=
|
|
p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
|
|
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
|
|
p->user != current->nsproxy->user_ns->root_user)
|
|
goto bad_fork_free;
|
|
}
|
|
|
|
atomic_inc(&p->user->__count);
|
|
atomic_inc(&p->user->processes);
|
|
get_group_info(p->group_info);
|
|
|
|
/*
|
|
* If multiple threads are within copy_process(), then this check
|
|
* triggers too late. This doesn't hurt, the check is only there
|
|
* to stop root fork bombs.
|
|
*/
|
|
if (nr_threads >= max_threads)
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (!try_module_get(task_thread_info(p)->exec_domain->module))
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (p->binfmt && !try_module_get(p->binfmt->module))
|
|
goto bad_fork_cleanup_put_domain;
|
|
|
|
p->did_exec = 0;
|
|
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
|
|
copy_flags(clone_flags, p);
|
|
INIT_LIST_HEAD(&p->children);
|
|
INIT_LIST_HEAD(&p->sibling);
|
|
#ifdef CONFIG_PREEMPT_RCU
|
|
p->rcu_read_lock_nesting = 0;
|
|
p->rcu_flipctr_idx = 0;
|
|
#endif /* #ifdef CONFIG_PREEMPT_RCU */
|
|
p->vfork_done = NULL;
|
|
spin_lock_init(&p->alloc_lock);
|
|
|
|
clear_tsk_thread_flag(p, TIF_SIGPENDING);
|
|
init_sigpending(&p->pending);
|
|
|
|
p->utime = cputime_zero;
|
|
p->stime = cputime_zero;
|
|
p->gtime = cputime_zero;
|
|
p->utimescaled = cputime_zero;
|
|
p->stimescaled = cputime_zero;
|
|
p->prev_utime = cputime_zero;
|
|
p->prev_stime = cputime_zero;
|
|
|
|
#ifdef CONFIG_DETECT_SOFTLOCKUP
|
|
p->last_switch_count = 0;
|
|
p->last_switch_timestamp = 0;
|
|
#endif
|
|
|
|
#ifdef CONFIG_TASK_XACCT
|
|
p->rchar = 0; /* I/O counter: bytes read */
|
|
p->wchar = 0; /* I/O counter: bytes written */
|
|
p->syscr = 0; /* I/O counter: read syscalls */
|
|
p->syscw = 0; /* I/O counter: write syscalls */
|
|
#endif
|
|
task_io_accounting_init(p);
|
|
acct_clear_integrals(p);
|
|
|
|
p->it_virt_expires = cputime_zero;
|
|
p->it_prof_expires = cputime_zero;
|
|
p->it_sched_expires = 0;
|
|
INIT_LIST_HEAD(&p->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&p->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&p->cpu_timers[2]);
|
|
|
|
p->lock_depth = -1; /* -1 = no lock */
|
|
do_posix_clock_monotonic_gettime(&p->start_time);
|
|
p->real_start_time = p->start_time;
|
|
monotonic_to_bootbased(&p->real_start_time);
|
|
#ifdef CONFIG_SECURITY
|
|
p->security = NULL;
|
|
#endif
|
|
p->cap_bset = current->cap_bset;
|
|
p->io_context = NULL;
|
|
p->audit_context = NULL;
|
|
cgroup_fork(p);
|
|
#ifdef CONFIG_NUMA
|
|
p->mempolicy = mpol_dup(p->mempolicy);
|
|
if (IS_ERR(p->mempolicy)) {
|
|
retval = PTR_ERR(p->mempolicy);
|
|
p->mempolicy = NULL;
|
|
goto bad_fork_cleanup_cgroup;
|
|
}
|
|
mpol_fix_fork_child_flag(p);
|
|
#endif
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
p->irq_events = 0;
|
|
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
|
|
p->hardirqs_enabled = 1;
|
|
#else
|
|
p->hardirqs_enabled = 0;
|
|
#endif
|
|
p->hardirq_enable_ip = 0;
|
|
p->hardirq_enable_event = 0;
|
|
p->hardirq_disable_ip = _THIS_IP_;
|
|
p->hardirq_disable_event = 0;
|
|
p->softirqs_enabled = 1;
|
|
p->softirq_enable_ip = _THIS_IP_;
|
|
p->softirq_enable_event = 0;
|
|
p->softirq_disable_ip = 0;
|
|
p->softirq_disable_event = 0;
|
|
p->hardirq_context = 0;
|
|
p->softirq_context = 0;
|
|
#endif
|
|
#ifdef CONFIG_LOCKDEP
|
|
p->lockdep_depth = 0; /* no locks held yet */
|
|
p->curr_chain_key = 0;
|
|
p->lockdep_recursion = 0;
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_MUTEXES
|
|
p->blocked_on = NULL; /* not blocked yet */
|
|
#endif
|
|
|
|
/* Perform scheduler related setup. Assign this task to a CPU. */
|
|
sched_fork(p, clone_flags);
|
|
|
|
if ((retval = security_task_alloc(p)))
|
|
goto bad_fork_cleanup_policy;
|
|
if ((retval = audit_alloc(p)))
|
|
goto bad_fork_cleanup_security;
|
|
/* copy all the process information */
|
|
if ((retval = copy_semundo(clone_flags, p)))
|
|
goto bad_fork_cleanup_audit;
|
|
if ((retval = copy_files(clone_flags, p)))
|
|
goto bad_fork_cleanup_semundo;
|
|
if ((retval = copy_fs(clone_flags, p)))
|
|
goto bad_fork_cleanup_files;
|
|
if ((retval = copy_sighand(clone_flags, p)))
|
|
goto bad_fork_cleanup_fs;
|
|
if ((retval = copy_signal(clone_flags, p)))
|
|
goto bad_fork_cleanup_sighand;
|
|
if ((retval = copy_mm(clone_flags, p)))
|
|
goto bad_fork_cleanup_signal;
|
|
if ((retval = copy_keys(clone_flags, p)))
|
|
goto bad_fork_cleanup_mm;
|
|
if ((retval = copy_namespaces(clone_flags, p)))
|
|
goto bad_fork_cleanup_keys;
|
|
if ((retval = copy_io(clone_flags, p)))
|
|
goto bad_fork_cleanup_namespaces;
|
|
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
|
|
if (retval)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (pid != &init_struct_pid) {
|
|
retval = -ENOMEM;
|
|
pid = alloc_pid(task_active_pid_ns(p));
|
|
if (!pid)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (clone_flags & CLONE_NEWPID) {
|
|
retval = pid_ns_prepare_proc(task_active_pid_ns(p));
|
|
if (retval < 0)
|
|
goto bad_fork_free_pid;
|
|
}
|
|
}
|
|
|
|
p->pid = pid_nr(pid);
|
|
p->tgid = p->pid;
|
|
if (clone_flags & CLONE_THREAD)
|
|
p->tgid = current->tgid;
|
|
|
|
if (current->nsproxy != p->nsproxy) {
|
|
retval = ns_cgroup_clone(p, pid);
|
|
if (retval)
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
|
|
/*
|
|
* Clear TID on mm_release()?
|
|
*/
|
|
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
|
|
#ifdef CONFIG_FUTEX
|
|
p->robust_list = NULL;
|
|
#ifdef CONFIG_COMPAT
|
|
p->compat_robust_list = NULL;
|
|
#endif
|
|
INIT_LIST_HEAD(&p->pi_state_list);
|
|
p->pi_state_cache = NULL;
|
|
#endif
|
|
/*
|
|
* sigaltstack should be cleared when sharing the same VM
|
|
*/
|
|
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
|
p->sas_ss_sp = p->sas_ss_size = 0;
|
|
|
|
/*
|
|
* Syscall tracing should be turned off in the child regardless
|
|
* of CLONE_PTRACE.
|
|
*/
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
|
|
#ifdef TIF_SYSCALL_EMU
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
|
|
#endif
|
|
clear_all_latency_tracing(p);
|
|
|
|
/* Our parent execution domain becomes current domain
|
|
These must match for thread signalling to apply */
|
|
p->parent_exec_id = p->self_exec_id;
|
|
|
|
/* ok, now we should be set up.. */
|
|
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
|
|
p->pdeath_signal = 0;
|
|
p->exit_state = 0;
|
|
|
|
/*
|
|
* Ok, make it visible to the rest of the system.
|
|
* We dont wake it up yet.
|
|
*/
|
|
p->group_leader = p;
|
|
INIT_LIST_HEAD(&p->thread_group);
|
|
INIT_LIST_HEAD(&p->ptrace_entry);
|
|
INIT_LIST_HEAD(&p->ptraced);
|
|
|
|
/* Now that the task is set up, run cgroup callbacks if
|
|
* necessary. We need to run them before the task is visible
|
|
* on the tasklist. */
|
|
cgroup_fork_callbacks(p);
|
|
cgroup_callbacks_done = 1;
|
|
|
|
/* Need tasklist lock for parent etc handling! */
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
/*
|
|
* The task hasn't been attached yet, so its cpus_allowed mask will
|
|
* not be changed, nor will its assigned CPU.
|
|
*
|
|
* The cpus_allowed mask of the parent may have changed after it was
|
|
* copied first time - so re-copy it here, then check the child's CPU
|
|
* to ensure it is on a valid CPU (and if not, just force it back to
|
|
* parent's CPU). This avoids alot of nasty races.
|
|
*/
|
|
p->cpus_allowed = current->cpus_allowed;
|
|
p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
|
|
if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
|
|
!cpu_online(task_cpu(p))))
|
|
set_task_cpu(p, smp_processor_id());
|
|
|
|
/* CLONE_PARENT re-uses the old parent */
|
|
if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
|
|
p->real_parent = current->real_parent;
|
|
else
|
|
p->real_parent = current;
|
|
p->parent = p->real_parent;
|
|
|
|
spin_lock(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Process group and session signals need to be delivered to just the
|
|
* parent before the fork or both the parent and the child after the
|
|
* fork. Restart if a signal comes in before we add the new process to
|
|
* it's process group.
|
|
* A fatal signal pending means that current will exit, so the new
|
|
* thread can't slip out of an OOM kill (or normal SIGKILL).
|
|
*/
|
|
recalc_sigpending();
|
|
if (signal_pending(current)) {
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
p->group_leader = current->group_leader;
|
|
list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
|
|
|
|
if (!cputime_eq(current->signal->it_virt_expires,
|
|
cputime_zero) ||
|
|
!cputime_eq(current->signal->it_prof_expires,
|
|
cputime_zero) ||
|
|
current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
|
|
!list_empty(¤t->signal->cpu_timers[0]) ||
|
|
!list_empty(¤t->signal->cpu_timers[1]) ||
|
|
!list_empty(¤t->signal->cpu_timers[2])) {
|
|
/*
|
|
* Have child wake up on its first tick to check
|
|
* for process CPU timers.
|
|
*/
|
|
p->it_prof_expires = jiffies_to_cputime(1);
|
|
}
|
|
}
|
|
|
|
if (likely(p->pid)) {
|
|
list_add_tail(&p->sibling, &p->real_parent->children);
|
|
if (unlikely(p->ptrace & PT_PTRACED))
|
|
__ptrace_link(p, current->parent);
|
|
|
|
if (thread_group_leader(p)) {
|
|
if (clone_flags & CLONE_NEWPID)
|
|
p->nsproxy->pid_ns->child_reaper = p;
|
|
|
|
p->signal->leader_pid = pid;
|
|
p->signal->tty = current->signal->tty;
|
|
set_task_pgrp(p, task_pgrp_nr(current));
|
|
set_task_session(p, task_session_nr(current));
|
|
attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
|
|
attach_pid(p, PIDTYPE_SID, task_session(current));
|
|
list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
|
__get_cpu_var(process_counts)++;
|
|
}
|
|
attach_pid(p, PIDTYPE_PID, pid);
|
|
nr_threads++;
|
|
}
|
|
|
|
total_forks++;
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
proc_fork_connector(p);
|
|
cgroup_post_fork(p);
|
|
return p;
|
|
|
|
bad_fork_free_pid:
|
|
if (pid != &init_struct_pid)
|
|
free_pid(pid);
|
|
bad_fork_cleanup_io:
|
|
put_io_context(p->io_context);
|
|
bad_fork_cleanup_namespaces:
|
|
exit_task_namespaces(p);
|
|
bad_fork_cleanup_keys:
|
|
exit_keys(p);
|
|
bad_fork_cleanup_mm:
|
|
if (p->mm)
|
|
mmput(p->mm);
|
|
bad_fork_cleanup_signal:
|
|
cleanup_signal(p);
|
|
bad_fork_cleanup_sighand:
|
|
__cleanup_sighand(p->sighand);
|
|
bad_fork_cleanup_fs:
|
|
exit_fs(p); /* blocking */
|
|
bad_fork_cleanup_files:
|
|
exit_files(p); /* blocking */
|
|
bad_fork_cleanup_semundo:
|
|
exit_sem(p);
|
|
bad_fork_cleanup_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_security:
|
|
security_task_free(p);
|
|
bad_fork_cleanup_policy:
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(p->mempolicy);
|
|
bad_fork_cleanup_cgroup:
|
|
#endif
|
|
cgroup_exit(p, cgroup_callbacks_done);
|
|
delayacct_tsk_free(p);
|
|
if (p->binfmt)
|
|
module_put(p->binfmt->module);
|
|
bad_fork_cleanup_put_domain:
|
|
module_put(task_thread_info(p)->exec_domain->module);
|
|
bad_fork_cleanup_count:
|
|
put_group_info(p->group_info);
|
|
atomic_dec(&p->user->processes);
|
|
free_uid(p->user);
|
|
bad_fork_free:
|
|
free_task(p);
|
|
fork_out:
|
|
return ERR_PTR(retval);
|
|
}
|
|
|
|
noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
|
|
{
|
|
memset(regs, 0, sizeof(struct pt_regs));
|
|
return regs;
|
|
}
|
|
|
|
struct task_struct * __cpuinit fork_idle(int cpu)
|
|
{
|
|
struct task_struct *task;
|
|
struct pt_regs regs;
|
|
|
|
task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
|
|
&init_struct_pid);
|
|
if (!IS_ERR(task))
|
|
init_idle(task, cpu);
|
|
|
|
return task;
|
|
}
|
|
|
|
static int fork_traceflag(unsigned clone_flags)
|
|
{
|
|
if (clone_flags & CLONE_UNTRACED)
|
|
return 0;
|
|
else if (clone_flags & CLONE_VFORK) {
|
|
if (current->ptrace & PT_TRACE_VFORK)
|
|
return PTRACE_EVENT_VFORK;
|
|
} else if ((clone_flags & CSIGNAL) != SIGCHLD) {
|
|
if (current->ptrace & PT_TRACE_CLONE)
|
|
return PTRACE_EVENT_CLONE;
|
|
} else if (current->ptrace & PT_TRACE_FORK)
|
|
return PTRACE_EVENT_FORK;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Ok, this is the main fork-routine.
|
|
*
|
|
* It copies the process, and if successful kick-starts
|
|
* it and waits for it to finish using the VM if required.
|
|
*/
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
struct task_struct *p;
|
|
int trace = 0;
|
|
long nr;
|
|
|
|
/*
|
|
* We hope to recycle these flags after 2.6.26
|
|
*/
|
|
if (unlikely(clone_flags & CLONE_STOPPED)) {
|
|
static int __read_mostly count = 100;
|
|
|
|
if (count > 0 && printk_ratelimit()) {
|
|
char comm[TASK_COMM_LEN];
|
|
|
|
count--;
|
|
printk(KERN_INFO "fork(): process `%s' used deprecated "
|
|
"clone flags 0x%lx\n",
|
|
get_task_comm(comm, current),
|
|
clone_flags & CLONE_STOPPED);
|
|
}
|
|
}
|
|
|
|
if (unlikely(current->ptrace)) {
|
|
trace = fork_traceflag (clone_flags);
|
|
if (trace)
|
|
clone_flags |= CLONE_PTRACE;
|
|
}
|
|
|
|
p = copy_process(clone_flags, stack_start, regs, stack_size,
|
|
child_tidptr, NULL);
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
if (!IS_ERR(p)) {
|
|
struct completion vfork;
|
|
|
|
nr = task_pid_vnr(p);
|
|
|
|
if (clone_flags & CLONE_PARENT_SETTID)
|
|
put_user(nr, parent_tidptr);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
p->vfork_done = &vfork;
|
|
init_completion(&vfork);
|
|
}
|
|
|
|
if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
|
|
/*
|
|
* We'll start up with an immediate SIGSTOP.
|
|
*/
|
|
sigaddset(&p->pending.signal, SIGSTOP);
|
|
set_tsk_thread_flag(p, TIF_SIGPENDING);
|
|
}
|
|
|
|
if (!(clone_flags & CLONE_STOPPED))
|
|
wake_up_new_task(p, clone_flags);
|
|
else
|
|
__set_task_state(p, TASK_STOPPED);
|
|
|
|
if (unlikely (trace)) {
|
|
current->ptrace_message = nr;
|
|
ptrace_notify ((trace << 8) | SIGTRAP);
|
|
}
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
freezer_do_not_count();
|
|
wait_for_completion(&vfork);
|
|
freezer_count();
|
|
if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
|
|
current->ptrace_message = nr;
|
|
ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
|
|
}
|
|
}
|
|
} else {
|
|
nr = PTR_ERR(p);
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
|
#define ARCH_MIN_MMSTRUCT_ALIGN 0
|
|
#endif
|
|
|
|
static void sighand_ctor(struct kmem_cache *cachep, void *data)
|
|
{
|
|
struct sighand_struct *sighand = data;
|
|
|
|
spin_lock_init(&sighand->siglock);
|
|
init_waitqueue_head(&sighand->signalfd_wqh);
|
|
}
|
|
|
|
void __init proc_caches_init(void)
|
|
{
|
|
sighand_cachep = kmem_cache_create("sighand_cache",
|
|
sizeof(struct sighand_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
|
|
sighand_ctor);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
|
vm_area_cachep = kmem_cache_create("vm_area_struct",
|
|
sizeof(struct vm_area_struct), 0,
|
|
SLAB_PANIC, NULL);
|
|
mm_cachep = kmem_cache_create("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
|
}
|
|
|
|
/*
|
|
* Check constraints on flags passed to the unshare system call and
|
|
* force unsharing of additional process context as appropriate.
|
|
*/
|
|
static void check_unshare_flags(unsigned long *flags_ptr)
|
|
{
|
|
/*
|
|
* If unsharing a thread from a thread group, must also
|
|
* unshare vm.
|
|
*/
|
|
if (*flags_ptr & CLONE_THREAD)
|
|
*flags_ptr |= CLONE_VM;
|
|
|
|
/*
|
|
* If unsharing vm, must also unshare signal handlers.
|
|
*/
|
|
if (*flags_ptr & CLONE_VM)
|
|
*flags_ptr |= CLONE_SIGHAND;
|
|
|
|
/*
|
|
* If unsharing signal handlers and the task was created
|
|
* using CLONE_THREAD, then must unshare the thread
|
|
*/
|
|
if ((*flags_ptr & CLONE_SIGHAND) &&
|
|
(atomic_read(¤t->signal->count) > 1))
|
|
*flags_ptr |= CLONE_THREAD;
|
|
|
|
/*
|
|
* If unsharing namespace, must also unshare filesystem information.
|
|
*/
|
|
if (*flags_ptr & CLONE_NEWNS)
|
|
*flags_ptr |= CLONE_FS;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of tasks created with CLONE_THREAD is not supported yet
|
|
*/
|
|
static int unshare_thread(unsigned long unshare_flags)
|
|
{
|
|
if (unshare_flags & CLONE_THREAD)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare the filesystem structure if it is being shared
|
|
*/
|
|
static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
|
|
if ((unshare_flags & CLONE_FS) &&
|
|
(fs && atomic_read(&fs->count) > 1)) {
|
|
*new_fsp = __copy_fs_struct(current->fs);
|
|
if (!*new_fsp)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of sighand is not supported yet
|
|
*/
|
|
static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
|
|
{
|
|
struct sighand_struct *sigh = current->sighand;
|
|
|
|
if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
|
|
return -EINVAL;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare vm if it is being shared
|
|
*/
|
|
static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
if ((unshare_flags & CLONE_VM) &&
|
|
(mm && atomic_read(&mm->mm_users) > 1)) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptor table if it is being shared
|
|
*/
|
|
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
|
{
|
|
struct files_struct *fd = current->files;
|
|
int error = 0;
|
|
|
|
if ((unshare_flags & CLONE_FILES) &&
|
|
(fd && atomic_read(&fd->count) > 1)) {
|
|
*new_fdp = dup_fd(fd, &error);
|
|
if (!*new_fdp)
|
|
return error;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* unshare allows a process to 'unshare' part of the process
|
|
* context which was originally shared using clone. copy_*
|
|
* functions used by do_fork() cannot be used here directly
|
|
* because they modify an inactive task_struct that is being
|
|
* constructed. Here we are modifying the current, active,
|
|
* task_struct.
|
|
*/
|
|
asmlinkage long sys_unshare(unsigned long unshare_flags)
|
|
{
|
|
int err = 0;
|
|
struct fs_struct *fs, *new_fs = NULL;
|
|
struct sighand_struct *new_sigh = NULL;
|
|
struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
|
|
struct files_struct *fd, *new_fd = NULL;
|
|
struct nsproxy *new_nsproxy = NULL;
|
|
int do_sysvsem = 0;
|
|
|
|
check_unshare_flags(&unshare_flags);
|
|
|
|
/* Return -EINVAL for all unsupported flags */
|
|
err = -EINVAL;
|
|
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
|
CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
|
|
CLONE_NEWNET))
|
|
goto bad_unshare_out;
|
|
|
|
/*
|
|
* CLONE_NEWIPC must also detach from the undolist: after switching
|
|
* to a new ipc namespace, the semaphore arrays from the old
|
|
* namespace are unreachable.
|
|
*/
|
|
if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
|
do_sysvsem = 1;
|
|
if ((err = unshare_thread(unshare_flags)))
|
|
goto bad_unshare_out;
|
|
if ((err = unshare_fs(unshare_flags, &new_fs)))
|
|
goto bad_unshare_cleanup_thread;
|
|
if ((err = unshare_sighand(unshare_flags, &new_sigh)))
|
|
goto bad_unshare_cleanup_fs;
|
|
if ((err = unshare_vm(unshare_flags, &new_mm)))
|
|
goto bad_unshare_cleanup_sigh;
|
|
if ((err = unshare_fd(unshare_flags, &new_fd)))
|
|
goto bad_unshare_cleanup_vm;
|
|
if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
|
|
new_fs)))
|
|
goto bad_unshare_cleanup_fd;
|
|
|
|
if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) {
|
|
if (do_sysvsem) {
|
|
/*
|
|
* CLONE_SYSVSEM is equivalent to sys_exit().
|
|
*/
|
|
exit_sem(current);
|
|
}
|
|
|
|
if (new_nsproxy) {
|
|
switch_task_namespaces(current, new_nsproxy);
|
|
new_nsproxy = NULL;
|
|
}
|
|
|
|
task_lock(current);
|
|
|
|
if (new_fs) {
|
|
fs = current->fs;
|
|
current->fs = new_fs;
|
|
new_fs = fs;
|
|
}
|
|
|
|
if (new_mm) {
|
|
mm = current->mm;
|
|
active_mm = current->active_mm;
|
|
current->mm = new_mm;
|
|
current->active_mm = new_mm;
|
|
activate_mm(active_mm, new_mm);
|
|
new_mm = mm;
|
|
}
|
|
|
|
if (new_fd) {
|
|
fd = current->files;
|
|
current->files = new_fd;
|
|
new_fd = fd;
|
|
}
|
|
|
|
task_unlock(current);
|
|
}
|
|
|
|
if (new_nsproxy)
|
|
put_nsproxy(new_nsproxy);
|
|
|
|
bad_unshare_cleanup_fd:
|
|
if (new_fd)
|
|
put_files_struct(new_fd);
|
|
|
|
bad_unshare_cleanup_vm:
|
|
if (new_mm)
|
|
mmput(new_mm);
|
|
|
|
bad_unshare_cleanup_sigh:
|
|
if (new_sigh)
|
|
if (atomic_dec_and_test(&new_sigh->count))
|
|
kmem_cache_free(sighand_cachep, new_sigh);
|
|
|
|
bad_unshare_cleanup_fs:
|
|
if (new_fs)
|
|
put_fs_struct(new_fs);
|
|
|
|
bad_unshare_cleanup_thread:
|
|
bad_unshare_out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Helper to unshare the files of the current task.
|
|
* We don't want to expose copy_files internals to
|
|
* the exec layer of the kernel.
|
|
*/
|
|
|
|
int unshare_files(struct files_struct **displaced)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct files_struct *copy = NULL;
|
|
int error;
|
|
|
|
error = unshare_fd(CLONE_FILES, ©);
|
|
if (error || !copy) {
|
|
*displaced = NULL;
|
|
return error;
|
|
}
|
|
*displaced = task->files;
|
|
task_lock(task);
|
|
task->files = copy;
|
|
task_unlock(task);
|
|
return 0;
|
|
}
|