linux-kernel - [PATCH] exec: move ->recursion_depth out of critical sections

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Date:   Thu, 18 Apr 2019 00:31:50 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] exec: move ->recursion_depth out of critical sections

->recursion_depth is changed only by current, therefore decrementing can be
done without taking any locks.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 fs/exec.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1652,11 +1652,13 @@ int search_binary_handler(struct linux_binprm *bprm)
 		if (!try_module_get(fmt->module))
 			continue;
 		read_unlock(&binfmt_lock);
+
 		bprm->recursion_depth++;
 		retval = fmt->load_binary(bprm);
+		bprm->recursion_depth--;
+
 		read_lock(&binfmt_lock);
 		put_binfmt(fmt);
-		bprm->recursion_depth--;
 		if (retval < 0 && !bprm->mm) {
 			/* we got to flush_old_exec() and failed after it */
 			read_unlock(&binfmt_lock);