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introduce "struct wait_opts" to simplify do_wait() patches 

Introduce "struct wait_opts" which holds the parameters for misc helpers
in do_wait() pathes.

This adds 13 lines to kernel/exit.c, but saves 256 bytes from .o and imho
makes the code much more readable.

This patch temporary uglifies rusage/siginfo code a little bit, will be
addressed by further cleanups.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2009-06-17 16:27:39 -07:00 committed by Linus Torvalds
parent 47918025ef
commit 9e8ae01d1c
1 changed files with 110 additions and 97 deletions
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207
kernel/exit.c
View File

@ -1080,6 +1080,18 @@ SYSCALL_DEFINE1(exit_group, int, error_code)
return 0;
}
struct wait_opts {
enum pid_type wo_type;
struct pid *wo_pid;
int wo_flags;
struct siginfo __user *wo_info;
int __user *wo_stat;
struct rusage __user *wo_rusage;
int notask_error;
};
static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
{
struct pid *pid = NULL;
@ -1090,13 +1102,12 @@ static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
return pid;
}
static int eligible_child(enum pid_type type, struct pid *pid, int options,
struct task_struct *p)
static int eligible_child(struct wait_opts *wo, struct task_struct *p)
{
int err;
if (type < PIDTYPE_MAX) {
if (task_pid_type(p, type) != pid)
if (wo->wo_type < PIDTYPE_MAX) {
if (task_pid_type(p, wo->wo_type) != wo->wo_pid)
return 0;
}
@ -1105,8 +1116,8 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options,
* set; otherwise, wait for non-clone children *only*. (Note:
* A "clone" child here is one that reports to its parent
* using a signal other than SIGCHLD.) */
if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
&& !(options & __WALL))
if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
&& !(wo->wo_flags & __WALL))
return 0;
err = security_task_wait(p);
@ -1116,14 +1127,15 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options,
return 1;
}
static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
int why, int status,
struct siginfo __user *infop,
struct rusage __user *rusagep)
static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
pid_t pid, uid_t uid, int why, int status)
{
int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
struct siginfo __user *infop;
int retval = wo->wo_rusage
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
put_task_struct(p);
infop = wo->wo_info;
if (!retval)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval)
@ -1147,19 +1159,18 @@ static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_zombie(struct task_struct *p, int options,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
{
unsigned long state;
int retval, status, traced;
pid_t pid = task_pid_vnr(p);
uid_t uid = __task_cred(p)->uid;
struct siginfo __user *infop;
if (!likely(options & WEXITED))
if (!likely(wo->wo_flags & WEXITED))
return 0;
if (unlikely(options & WNOWAIT)) {
if (unlikely(wo->wo_flags & WNOWAIT)) {
int exit_code = p->exit_code;
int why, status;
@ -1172,8 +1183,7 @@ static int wait_task_zombie(struct task_struct *p, int options,
why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
status = exit_code & 0x7f;
}
return wait_noreap_copyout(p, pid, uid, why,
status, infop, ru);
return wait_noreap_copyout(wo, p, pid, uid, why, status);
}
/*
@ -1250,11 +1260,14 @@ static int wait_task_zombie(struct task_struct *p, int options,
*/
read_unlock(&tasklist_lock);
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
retval = wo->wo_rusage
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
status = (p->signal->flags & SIGNAL_GROUP_EXIT)
? p->signal->group_exit_code : p->exit_code;
if (!retval && stat_addr)
retval = put_user(status, stat_addr);
if (!retval && wo->wo_stat)
retval = put_user(status, wo->wo_stat);
infop = wo->wo_info;
if (!retval && infop)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval && infop)
@ -1322,10 +1335,10 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace)
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_stopped(int ptrace, struct task_struct *p,
int options, struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
static int wait_task_stopped(struct wait_opts *wo,
int ptrace, struct task_struct *p)
{
struct siginfo __user *infop;
int retval, exit_code, *p_code, why;
uid_t uid = 0; /* unneeded, required by compiler */
pid_t pid;
@ -1333,7 +1346,7 @@ static int wait_task_stopped(int ptrace, struct task_struct *p,
/*
* Traditionally we see ptrace'd stopped tasks regardless of options.
*/
if (!ptrace && !(options & WUNTRACED))
if (!ptrace && !(wo->wo_flags & WUNTRACED))
return 0;
exit_code = 0;
@ -1347,7 +1360,7 @@ static int wait_task_stopped(int ptrace, struct task_struct *p,
if (!exit_code)
goto unlock_sig;
if (!unlikely(options & WNOWAIT))
if (!unlikely(wo->wo_flags & WNOWAIT))
*p_code = 0;
/* don't need the RCU readlock here as we're holding a spinlock */
@ -1369,14 +1382,15 @@ unlock_sig:
why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
read_unlock(&tasklist_lock);
if (unlikely(options & WNOWAIT))
return wait_noreap_copyout(p, pid, uid,
why, exit_code,
infop, ru);
if (unlikely(wo->wo_flags & WNOWAIT))
return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
if (!retval && stat_addr)
retval = put_user((exit_code << 8) | 0x7f, stat_addr);
retval = wo->wo_rusage
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
if (!retval && wo->wo_stat)
retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
infop = wo->wo_info;
if (!retval && infop)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval && infop)
@ -1403,15 +1417,13 @@ unlock_sig:
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_continued(struct task_struct *p, int options,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
{
int retval;
pid_t pid;
uid_t uid;
if (!unlikely(options & WCONTINUED))
if (!unlikely(wo->wo_flags & WCONTINUED))
return 0;
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
@ -1423,7 +1435,7 @@ static int wait_task_continued(struct task_struct *p, int options,
spin_unlock_irq(&p->sighand->siglock);
return 0;
}
if (!unlikely(options & WNOWAIT))
if (!unlikely(wo->wo_flags & WNOWAIT))
p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
uid = __task_cred(p)->uid;
spin_unlock_irq(&p->sighand->siglock);
@ -1432,17 +1444,17 @@ static int wait_task_continued(struct task_struct *p, int options,
get_task_struct(p);
read_unlock(&tasklist_lock);
if (!infop) {
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
if (!wo->wo_info) {
retval = wo->wo_rusage
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
put_task_struct(p);
if (!retval && stat_addr)
retval = put_user(0xffff, stat_addr);
if (!retval && wo->wo_stat)
retval = put_user(0xffff, wo->wo_stat);
if (!retval)
retval = pid;
} else {
retval = wait_noreap_copyout(p, pid, uid,
CLD_CONTINUED, SIGCONT,
infop, ru);
retval = wait_noreap_copyout(wo, p, pid, uid,
CLD_CONTINUED, SIGCONT);
BUG_ON(retval == 0);
}
@ -1452,19 +1464,16 @@ static int wait_task_continued(struct task_struct *p, int options,
/*
* Consider @p for a wait by @parent.
*
* -ECHILD should be in *@notask_error before the first call.
* -ECHILD should be in ->notask_error before the first call.
* Returns nonzero for a final return, when we have unlocked tasklist_lock.
* Returns zero if the search for a child should continue;
* then *@notask_error is 0 if @p is an eligible child,
* then ->notask_error is 0 if @p is an eligible child,
* or another error from security_task_wait(), or still -ECHILD.
*/
static int wait_consider_task(struct task_struct *parent, int ptrace,
struct task_struct *p, int *notask_error,
enum pid_type type, struct pid *pid, int options,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
static int wait_consider_task(struct wait_opts *wo, struct task_struct *parent,
int ptrace, struct task_struct *p)
{
int ret = eligible_child(type, pid, options, p);
int ret = eligible_child(wo, p);
if (!ret)
return ret;
@ -1476,8 +1485,8 @@ static int wait_consider_task(struct task_struct *parent, int ptrace,
* to look for security policy problems, rather
* than for mysterious wait bugs.
*/
if (*notask_error)
*notask_error = ret;
if (wo->notask_error)
wo->notask_error = ret;
return 0;
}
@ -1486,7 +1495,7 @@ static int wait_consider_task(struct task_struct *parent, int ptrace,
* This child is hidden by ptrace.
* We aren't allowed to see it now, but eventually we will.
*/
*notask_error = 0;
wo->notask_error = 0;
return 0;
}
@ -1497,34 +1506,30 @@ static int wait_consider_task(struct task_struct *parent, int ptrace,
* We don't reap group leaders with subthreads.
*/
if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
return wait_task_zombie(p, options, infop, stat_addr, ru);
return wait_task_zombie(wo, p);
/*
* It's stopped or running now, so it might
* later continue, exit, or stop again.
*/
*notask_error = 0;
wo->notask_error = 0;
if (task_stopped_code(p, ptrace))
return wait_task_stopped(ptrace, p, options,
infop, stat_addr, ru);
return wait_task_stopped(wo, ptrace, p);
return wait_task_continued(p, options, infop, stat_addr, ru);
return wait_task_continued(wo, p);
}
/*
* Do the work of do_wait() for one thread in the group, @tsk.
*
* -ECHILD should be in *@notask_error before the first call.
* -ECHILD should be in ->notask_error before the first call.
* Returns nonzero for a final return, when we have unlocked tasklist_lock.
* Returns zero if the search for a child should continue; then
* *@notask_error is 0 if there were any eligible children,
* ->notask_error is 0 if there were any eligible children,
* or another error from security_task_wait(), or still -ECHILD.
*/
static int do_wait_thread(struct task_struct *tsk, int *notask_error,
enum pid_type type, struct pid *pid, int options,
struct siginfo __user *infop, int __user *stat_addr,
struct rusage __user *ru)
static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
{
struct task_struct *p;
@ -1533,9 +1538,7 @@ static int do_wait_thread(struct task_struct *tsk, int *notask_error,
* Do not consider detached threads.
*/
if (!task_detached(p)) {
int ret = wait_consider_task(tsk, 0, p, notask_error,
type, pid, options,
infop, stat_addr, ru);
int ret = wait_consider_task(wo, tsk, 0, p);
if (ret)
return ret;
}
@ -1544,17 +1547,12 @@ static int do_wait_thread(struct task_struct *tsk, int *notask_error,
return 0;
}
static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
enum pid_type type, struct pid *pid, int options,
struct siginfo __user *infop, int __user *stat_addr,
struct rusage __user *ru)
static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
{
struct task_struct *p;
list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
int ret = wait_consider_task(tsk, 1, p, notask_error,
type, pid, options,
infop, stat_addr, ru);
int ret = wait_consider_task(wo, tsk, 1, p);
if (ret)
return ret;
}
@ -1562,38 +1560,36 @@ static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
return 0;
}
static long do_wait(enum pid_type type, struct pid *pid, int options,
struct siginfo __user *infop, int __user *stat_addr,
struct rusage __user *ru)
static long do_wait(struct wait_opts *wo)
{
DECLARE_WAITQUEUE(wait, current);
struct task_struct *tsk;
int retval;
trace_sched_process_wait(pid);
trace_sched_process_wait(wo->wo_pid);
add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
/*
* If there is nothing that can match our critiera just get out.
* We will clear @retval to zero if we see any child that might later
* match our criteria, even if we are not able to reap it yet.
* We will clear ->notask_error to zero if we see any child that
* might later match our criteria, even if we are not able to reap
* it yet.
*/
retval = -ECHILD;
if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
retval = wo->notask_error = -ECHILD;
if ((wo->wo_type < PIDTYPE_MAX) &&
(!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
goto end;
current->state = TASK_INTERRUPTIBLE;
read_lock(&tasklist_lock);
tsk = current;
do {
int tsk_result = do_wait_thread(tsk, &retval,
type, pid, options,
infop, stat_addr, ru);
int tsk_result = do_wait_thread(wo, tsk);
if (!tsk_result)
tsk_result = ptrace_do_wait(tsk, &retval,
type, pid, options,
infop, stat_addr, ru);
tsk_result = ptrace_do_wait(wo, tsk);
if (tsk_result) {
/*
* tasklist_lock is unlocked and we have a final result.
@ -1602,25 +1598,27 @@ repeat:
goto end;
}
if (options & __WNOTHREAD)
if (wo->wo_flags & __WNOTHREAD)
break;
tsk = next_thread(tsk);
BUG_ON(tsk->signal != current->signal);
} while (tsk != current);
read_unlock(&tasklist_lock);
if (!retval && !(options & WNOHANG)) {
retval = wo->notask_error;
if (!retval && !(wo->wo_flags & WNOHANG)) {
retval = -ERESTARTSYS;
if (!signal_pending(current)) {
schedule();
goto repeat;
}
}
end:
current->state = TASK_RUNNING;
remove_wait_queue(&current->signal->wait_chldexit,&wait);
if (infop) {
if (wo->wo_info) {
struct siginfo __user *infop = wo->wo_info;
if (retval > 0)
retval = 0;
else {
@ -1649,6 +1647,7 @@ end:
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
infop, int, options, struct rusage __user *, ru)
{
struct wait_opts wo;
struct pid *pid = NULL;
enum pid_type type;
long ret;
@ -1678,7 +1677,14 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
if (type < PIDTYPE_MAX)
pid = find_get_pid(upid);
ret = do_wait(type, pid, options, infop, NULL, ru);
wo.wo_type = type;
wo.wo_pid = pid;
wo.wo_flags = options;
wo.wo_info = infop;
wo.wo_stat = NULL;
wo.wo_rusage = ru;
ret = do_wait(&wo);
put_pid(pid);
/* avoid REGPARM breakage on x86: */
@ -1689,6 +1695,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
int, options, struct rusage __user *, ru)
{
struct wait_opts wo;
struct pid *pid = NULL;
enum pid_type type;
long ret;
@ -1710,7 +1717,13 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
pid = find_get_pid(upid);
}
ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
wo.wo_type = type;
wo.wo_pid = pid;
wo.wo_flags = options | WEXITED;
wo.wo_info = NULL;
wo.wo_stat = stat_addr;
wo.wo_rusage = ru;
ret = do_wait(&wo);
put_pid(pid);
/* avoid REGPARM breakage on x86: */