coredump: turn core_state->nr_threads into atomic_t
Turn core_state->nr_threads into atomic_t and kill now unneeded
down_write(&mm->mmap_sem) in exit_mm().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index 988e232..63d8295 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -678,10 +678,9 @@
down_read(&mm->mmap_sem);
if (mm->core_state) {
up_read(&mm->mmap_sem);
- down_write(&mm->mmap_sem);
- if (!--mm->core_state->nr_threads)
+
+ if (atomic_dec_and_test(&mm->core_state->nr_threads))
complete(&mm->core_state->startup);
- up_write(&mm->mmap_sem);
wait_for_completion(&mm->core_done);
down_read(&mm->mmap_sem);