From 2ce802f62ba32a7d95748ac92bf351f76affb6ff Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 20 Jan 2011 12:06:35 +0100 Subject: [PATCH 1/2] lockdep: Move early boot local IRQ enable/disable status to init/main.c During early boot, local IRQ is disabled until IRQ subsystem is properly initialized. During this time, no one should enable local IRQ and some operations which usually are not allowed with IRQ disabled, e.g. operations which might sleep or require communications with other processors, are allowed. lockdep tracked this with early_boot_irqs_off/on() callbacks. As other subsystems need this information too, move it to init/main.c and make it generally available. While at it, toggle the boolean to early_boot_irqs_disabled instead of enabled so that it can be initialized with %false and %true indicates the exceptional condition. Signed-off-by: Tejun Heo Acked-by: Peter Zijlstra Acked-by: Pekka Enberg Cc: Linus Torvalds LKML-Reference: <20110120110635.GB6036@htj.dyndns.org> Signed-off-by: Ingo Molnar --- arch/x86/xen/enlighten.c | 2 +- include/linux/kernel.h | 2 ++ include/linux/lockdep.h | 8 -------- init/main.c | 13 +++++++++++-- kernel/lockdep.c | 18 +----------------- kernel/trace/trace_irqsoff.c | 8 -------- 6 files changed, 15 insertions(+), 36 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 7e8d3bc80af..50542efe45f 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1194,7 +1194,7 @@ asmlinkage void __init xen_start_kernel(void) per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0]; local_irq_disable(); - early_boot_irqs_off(); + early_boot_irqs_disabled = true; memblock_init(); diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 5a9d9059520..d07d8057e44 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -243,6 +243,8 @@ extern int test_taint(unsigned flag); extern unsigned long get_taint(void); extern int root_mountflags; +extern bool early_boot_irqs_disabled; + /* Values used for system_state */ extern enum system_states { SYSTEM_BOOTING, diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 71c09b26c75..f638fd78d10 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -436,16 +436,8 @@ do { \ #endif /* CONFIG_LOCKDEP */ #ifdef CONFIG_TRACE_IRQFLAGS -extern void early_boot_irqs_off(void); -extern void early_boot_irqs_on(void); extern void print_irqtrace_events(struct task_struct *curr); #else -static inline void early_boot_irqs_off(void) -{ -} -static inline void early_boot_irqs_on(void) -{ -} static inline void print_irqtrace_events(struct task_struct *curr) { } diff --git a/init/main.c b/init/main.c index 00799c1d462..33c37c379e9 100644 --- a/init/main.c +++ b/init/main.c @@ -96,6 +96,15 @@ static inline void mark_rodata_ro(void) { } extern void tc_init(void); #endif +/* + * Debug helper: via this flag we know that we are in 'early bootup code' + * where only the boot processor is running with IRQ disabled. This means + * two things - IRQ must not be enabled before the flag is cleared and some + * operations which are not allowed with IRQ disabled are allowed while the + * flag is set. + */ +bool early_boot_irqs_disabled __read_mostly; + enum system_states system_state __read_mostly; EXPORT_SYMBOL(system_state); @@ -554,7 +563,7 @@ asmlinkage void __init start_kernel(void) cgroup_init_early(); local_irq_disable(); - early_boot_irqs_off(); + early_boot_irqs_disabled = true; /* * Interrupts are still disabled. Do necessary setups, then @@ -621,7 +630,7 @@ asmlinkage void __init start_kernel(void) if (!irqs_disabled()) printk(KERN_CRIT "start_kernel(): bug: interrupts were " "enabled early\n"); - early_boot_irqs_on(); + early_boot_irqs_disabled = false; local_irq_enable(); /* Interrupts are enabled now so all GFP allocations are safe. */ diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 42ba65dff7d..0d2058da80f 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -2291,22 +2291,6 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark) return 1; } -/* - * Debugging helper: via this flag we know that we are in - * 'early bootup code', and will warn about any invalid irqs-on event: - */ -static int early_boot_irqs_enabled; - -void early_boot_irqs_off(void) -{ - early_boot_irqs_enabled = 0; -} - -void early_boot_irqs_on(void) -{ - early_boot_irqs_enabled = 1; -} - /* * Hardirqs will be enabled: */ @@ -2319,7 +2303,7 @@ void trace_hardirqs_on_caller(unsigned long ip) if (unlikely(!debug_locks || current->lockdep_recursion)) return; - if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) + if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) return; if (unlikely(curr->hardirqs_enabled)) { diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 5cf8c602b88..92b6e1e12d9 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -453,14 +453,6 @@ void time_hardirqs_off(unsigned long a0, unsigned long a1) * Stubs: */ -void early_boot_irqs_off(void) -{ -} - -void early_boot_irqs_on(void) -{ -} - void trace_softirqs_on(unsigned long ip) { } From bd924e8cbd4b73ffb7d707a774c04f7e2cae88ed Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 20 Jan 2011 12:07:13 +0100 Subject: [PATCH 2/2] smp: Allow on_each_cpu() to be called while early_boot_irqs_disabled status to init/main.c percpu may end up calling vfree() during early boot which in turn may call on_each_cpu() for TLB flushes. The function of on_each_cpu() can be done safely while IRQ is disabled during early boot but it assumed that the function is always called with local IRQ enabled which ended up enabling local IRQ prematurely during boot and triggering a couple of warnings. This patch updates on_each_cpu() and smp_call_function_many() such on_each_cpu() can be used safely while early_boot_irqs_disabled is set. Signed-off-by: Tejun Heo Acked-by: Peter Zijlstra Acked-by: Pekka Enberg Cc: Linus Torvalds LKML-Reference: <20110120110713.GC6036@htj.dyndns.org> Signed-off-by: Ingo Molnar Reported-by: Ingo Molnar --- kernel/smp.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/smp.c b/kernel/smp.c index 4ec30e06998..4b83cd6815e 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -430,7 +430,7 @@ void smp_call_function_many(const struct cpumask *mask, * can't happen. */ WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() - && !oops_in_progress); + && !oops_in_progress && !early_boot_irqs_disabled); /* So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask); @@ -533,17 +533,20 @@ void ipi_call_unlock_irq(void) #endif /* USE_GENERIC_SMP_HELPERS */ /* - * Call a function on all processors + * Call a function on all processors. May be used during early boot while + * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead + * of local_irq_disable/enable(). */ int on_each_cpu(void (*func) (void *info), void *info, int wait) { + unsigned long flags; int ret = 0; preempt_disable(); ret = smp_call_function(func, info, wait); - local_irq_disable(); + local_irq_save(flags); func(info); - local_irq_enable(); + local_irq_restore(flags); preempt_enable(); return ret; }