From 5debfa6da5b06954bc79fe8deed0d1062c58dcec Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 26 Jun 2006 00:26:09 -0700 Subject: [PATCH] [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 Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 8c8f2894949d..c8494f513eaf 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -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; } -- 2.20.1