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authorOleg Nesterov <oleg@redhat.com>2009-06-17 19:27:23 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 16:03:48 -0400
commit87245135d5057edd5a8037131f81eeffd76d4fef (patch)
tree9c6c695f474dfced54311467fd5c14de57f6dbb9
parent2ffebca6aa7e1687905c842dd8c5c1e811e574e7 (diff)
allow_signal: kill the bogus ->mm check, add a note about CLONE_SIGHAND
allow_signal() checks ->mm == NULL. Not sure why. Perhaps to make sure current is the kernel thread. But this helper must not be used unless we are the kernel thread, kill this check. Also, document the fact that the CLONE_SIGHAND kthread must not use allow_signal(), unless the caller really wants to change the parent's ->sighand->action as well. Signed-off-by: Oleg Nesterov <oleg@redhat.com> 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>
-rw-r--r--kernel/exit.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index b6c90b5ef509..533e5f85669a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -375,9 +375,8 @@ static void set_special_pids(struct pid *pid)
375} 375}
376 376
377/* 377/*
378 * Let kernel threads use this to say that they 378 * Let kernel threads use this to say that they allow a certain signal.
379 * allow a certain signal (since daemonize() will 379 * Must not be used if kthread was cloned with CLONE_SIGHAND.
380 * have disabled all of them by default).
381 */ 380 */
382int allow_signal(int sig) 381int allow_signal(int sig)
383{ 382{
@@ -385,14 +384,14 @@ int allow_signal(int sig)
385 return -EINVAL; 384 return -EINVAL;
386 385
387 spin_lock_irq(&current->sighand->siglock); 386 spin_lock_irq(&current->sighand->siglock);
387 /* This is only needed for daemonize()'ed kthreads */
388 sigdelset(&current->blocked, sig); 388 sigdelset(&current->blocked, sig);
389 if (!current->mm) { 389 /*
390 /* Kernel threads handle their own signals. 390 * Kernel threads handle their own signals. Let the signal code
391 Let the signal code know it'll be handled, so 391 * know it'll be handled, so that they don't get converted to
392 that they don't get converted to SIGKILL or 392 * SIGKILL or just silently dropped.
393 just silently dropped */ 393 */
394 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 394 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
395 }
396 recalc_sigpending(); 395 recalc_sigpending();
397 spin_unlock_irq(&current->sighand->siglock); 396 spin_unlock_irq(&current->sighand->siglock);
398 return 0; 397 return 0;