Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=abd96ecb298675a21c412a29f5de2f80174d5f18
Commit: abd96ecb298675a21c412a29f5de2f80174d5f18
Parent: 5c076fce2e217240b44bc753a5ec8ecd379c6eb9
Author: Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Wed Aug 22 14:01:58 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Aug 22 19:52:47 2007 -0700
exec: kill unsafe BUG_ON(sig->count) checks
de_thread:
if (atomic_read(&oldsighand->count) <= 1)
BUG_ON(atomic_read(&sig->count) != 1);
This is not safe without the rmb() in between. The results of two
correctly ordered __exit_signal()->atomic_dec_and_test()'s could be seen
out of order on our CPU.
The same is true for the "thread_group_empty()" case, __unhash_process()'s
changes could be seen before atomic_dec_and_test(&sig->count).
On some platforms (including i386) atomic_read() doesn't provide even the
compiler barrier, in that case these checks are simply racy.
Remove these BUG_ON()'s. Alternatively, we can do something like
BUG_ON( ({ smp_rmb(); atomic_read(&sig->count) != 1; }) );
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
Acked-by: Paul E. McKenney <[EMAIL PROTECTED]>
Cc: Roland McGrath <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
fs/exec.c | 3 ---
1 files changed, 0 insertions(+), 3 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index af4361c..c21a8cc 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -784,7 +784,6 @@ static int de_thread(struct task_struct *tsk)
* and we can just re-use it all.
*/
if (atomic_read(&oldsighand->count) <= 1) {
- BUG_ON(atomic_read(&sig->count) != 1);
signalfd_detach(tsk);
exit_itimers(sig);
return 0;
@@ -929,8 +928,6 @@ no_thread_group:
if (leader)
release_task(leader);
- BUG_ON(atomic_read(&sig->count) != 1);
-
if (atomic_read(&oldsighand->count) == 1) {
/*
* Now that we nuked the rest of the thread group,
-
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