[PATCH] coredump: speedup SIGKILL sending

With this patch a thread group is killed atomically under ->siglock.  This is
faster because we can use sigaddset() instead of force_sig_info() and this is
used in further patches.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 80fe7bcfa094..a5c51646d1ad 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1371,17 +1371,24 @@ static void format_corename(char *corename, const char *pattern, long signr)
 static void zap_process(struct task_struct *start, int *ptraced)
 {
         struct task_struct *t;
+        unsigned long flags;
+
+        spin_lock_irqsave(&start->sighand->siglock, flags);
 
         t = start;
         do {
                 if (t != current && t->mm) {
                         t->mm->core_waiters++;
-                        force_sig_specific(SIGKILL, t);
+                        sigaddset(&t->pending.signal, SIGKILL);
+                        signal_wake_up(t, 1);
+
                         if (unlikely(t->ptrace) &&
                             unlikely(t->parent->mm == t->mm))
                                 *ptraced = 1;
                 }
         } while ((t = next_thread(t)) != start);
+
+        spin_unlock_irqrestore(&start->sighand->siglock, flags);
 }
 
 static void zap_threads (struct mm_struct *mm)