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 <[email protected]>
include/linux/mm_types.h | 2 +-
kernel/exit.c | 5 ++---
fs/exec.c | 2 +-
3 files changed, 4 insertions(+), 5 deletions(-)
--- 26-rc2/include/linux/mm_types.h~4_NR_ATOMIC 2008-06-15 15:26:29.000000000 +0400
+++ 26-rc2/include/linux/mm_types.h 2008-06-16 18:00:08.000000000 +0400
@@ -160,7 +160,7 @@ struct vm_area_struct {
};
struct core_state {
- int nr_threads;
+ atomic_t nr_threads;
struct completion startup;
};
--- 26-rc2/kernel/exit.c~4_NR_ATOMIC 2008-06-15 15:28:21.000000000 +0400
+++ 26-rc2/kernel/exit.c 2008-06-16 19:58:59.000000000 +0400
@@ -667,10 +667,9 @@ static void exit_mm(struct task_struct *
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);
--- 26-rc2/fs/exec.c~4_NR_ATOMIC 2008-06-16 17:23:59.000000000 +0400
+++ 26-rc2/fs/exec.c 2008-06-16 19:59:26.000000000 +0400
@@ -1585,7 +1585,7 @@ static inline int zap_threads(struct tas
}
rcu_read_unlock();
done:
- core_state->nr_threads = nr;
+ atomic_set(&core_state->nr_threads, nr);
mm->core_state = core_state;
return nr;
}