Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d12619b5ff5664623524aef796514d1946ea3b4a
Commit: d12619b5ff5664623524aef796514d1946ea3b4a
Parent: 430c623121ea88ca80595c99fdc63b7f8a803ae5
Author: Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 8 04:19:12 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Feb 8 09:22:27 2008 -0800
fix group stop with exit race
do_signal_stop() counts all sub-thread and sets ->group_stop_count
accordingly. Every thread should decrement ->group_stop_count and stop,
the last one should notify the parent.
However a sub-thread can exit before it notices the signal_pending(), or it
may be somewhere in do_exit() already. In that case the group stop never
finishes properly.
Note: this is a minimal fix, we can add some optimizations later. Say we
can return quickly if thread_group_empty(). Also, we can move some signal
related code from exit_notify() to exit_signals().
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
Acked-by: Davide Libenzi <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
Cc: Roland McGrath <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
include/linux/signal.h | 1 +
kernel/exit.c | 2 +-
kernel/signal.c | 27 ++++++++++++++++++++++++++-
3 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 7e09514..42d2e0a 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -241,6 +241,7 @@ extern int show_unhandled_signals;
struct pt_regs;
extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction
*return_ka, struct pt_regs *regs, void *cookie);
+extern void exit_signals(struct task_struct *tsk);
extern struct kmem_cache *sighand_cachep;
diff --git a/kernel/exit.c b/kernel/exit.c
index d7815f5..8f3bf53 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -947,7 +947,7 @@ fastcall NORET_TYPE void do_exit(long code)
schedule();
}
- tsk->flags |= PF_EXITING;
+ exit_signals(tsk); /* sets PF_EXITING */
/*
* tsk->flags are checked in the futex code to protect against
* an exiting task cleaning up the robust pi futexes.
diff --git a/kernel/signal.c b/kernel/signal.c
index 3fca710..209eec1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1739,7 +1739,7 @@ static int do_signal_stop(int signr)
* stop is always done with the siglock held,
* so this check has no races.
*/
- if (!t->exit_state &&
+ if (!(t->flags & PF_EXITING) &&
!task_is_stopped_or_traced(t)) {
stop_count++;
signal_wake_up(t, 0);
@@ -1900,6 +1900,31 @@ relock:
return signr;
}
+void exit_signals(struct task_struct *tsk)
+{
+ int group_stop = 0;
+
+ spin_lock_irq(&tsk->sighand->siglock);
+ if (unlikely(tsk->signal->group_stop_count) &&
+ !--tsk->signal->group_stop_count) {
+ tsk->signal->flags = SIGNAL_STOP_STOPPED;
+ group_stop = 1;
+ }
+
+ /*
+ * From now this task is not visible for group-wide signals,
+ * see wants_signal(), do_signal_stop().
+ */
+ tsk->flags |= PF_EXITING;
+ spin_unlock_irq(&tsk->sighand->siglock);
+
+ if (unlikely(group_stop)) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(tsk, CLD_STOPPED);
+ read_unlock(&tasklist_lock);
+ }
+}
+
EXPORT_SYMBOL(recalc_sigpending);
EXPORT_SYMBOL_GPL(dequeue_signal);
EXPORT_SYMBOL(flush_signals);
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
