[RFC PATCH] locks:Remove spinlock in unshare_files

[ling.ma.program@gmail.com]

From: Ma Ling <ling.ml@antfin.com>

Processor support atomic operation for long/int/short/char type,
we use the feature to avoid spinlock, which cost hundreds cycles.

Appreciate your comments
Ling

Signed-off-by: Ma Ling <ling.ml@antfin.com>
---
 kernel/fork.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 60a1295..fe54600 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -3041,9 +3041,7 @@ int unshare_files(struct files_struct **displaced)
 		return error;
 	}
 	*displaced = task->files;
-	task_lock(task);
-	task->files = copy;
-	task_unlock(task);
+	WRITE_ONCE(task->files, copy);
 	return 0;
 }
 
-- 
1.8.3.1