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[PATCH] coredump: shutdown current process first 

This patch optimizes zap_threads() for the case when there are no ->mm
users except the current's thread group.  In that case we can avoid
'for_each_process()' loop.

It also adds a useful invariant: SIGNAL_GROUP_EXIT (if checked under
->siglock) always implies that all threads (except may be current) have
pending SIGKILL.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-06-26 00:26:09 -07:00 committed by Linus Torvalds
parent dcf560c593
commit 5debfa6da5
1 changed files with 17 additions and 12 deletions
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29
fs/exec.c
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@ -1371,13 +1371,7 @@ static void format_corename(char *corename, const char *pattern, long signr)
static void zap_process(struct task_struct *start)
{
struct task_struct *t;
unsigned long flags;
/*
* start->sighand can't disappear, but may be
* changed by de_thread()
*/
lock_task_sighand(start, &flags);
start->signal->flags = SIGNAL_GROUP_EXIT;
start->signal->group_stop_count = 0;
@ -1389,40 +1383,51 @@ static void zap_process(struct task_struct *start)
signal_wake_up(t, 1);
}
} while ((t = next_thread(t)) != start);
unlock_task_sighand(start, &flags);
}
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
int exit_code)
{
struct task_struct *g, *p;
unsigned long flags;
int err = -EAGAIN;
spin_lock_irq(&tsk->sighand->siglock);
if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
tsk->signal->flags = SIGNAL_GROUP_EXIT;
tsk->signal->group_exit_code = exit_code;
tsk->signal->group_stop_count = 0;
zap_process(tsk);
err = 0;
}
spin_unlock_irq(&tsk->sighand->siglock);
if (err)
return err;
if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
goto done;
rcu_read_lock();
for_each_process(g) {
if (g == tsk->group_leader)
continue;
p = g;
do {
if (p->mm) {
if (p->mm == mm)
if (p->mm == mm) {
/*
* p->sighand can't disappear, but
* may be changed by de_thread()
*/
lock_task_sighand(p, &flags);
zap_process(p);
unlock_task_sighand(p, &flags);
}
break;
}
} while ((p = next_thread(p)) != g);
}
rcu_read_unlock();
done:
return mm->core_waiters;
}