linux-kernel - [PATCH 11/16] seccomp: Replace smp_read_barrier_depends() with lockless

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Date:	Thu, 13 Nov 2014 14:24:17 -0500
From:	Pranith Kumar <bobby.prani@...il.com>
To:	Kees Cook <keescook@...omium.org>,
	Andy Lutomirski <luto@...capital.net>,
	Will Drewry <wad@...omium.org>,
	linux-kernel@...r.kernel.org (open list)
Cc:	paulmck@...ux.vnet.ibm.com
Subject: [PATCH 11/16] seccomp: Replace smp_read_barrier_depends() with lockless_dereference()

Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.

Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
 kernel/seccomp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4ef9687..3729b06 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -175,17 +175,16 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
  */
 static u32 seccomp_run_filters(struct seccomp_data *sd)
 {
-	struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
 	struct seccomp_data sd_local;
 	u32 ret = SECCOMP_RET_ALLOW;
+	/* Make sure cross-thread synced filter points somewhere sane. */
+	struct seccomp_filter *f =
+			lockless_dereference(current->seccomp.filter);
 
 	/* Ensure unexpected behavior doesn't result in failing open. */
 	if (unlikely(WARN_ON(f == NULL)))
 		return SECCOMP_RET_KILL;
 
-	/* Make sure cross-thread synced filter points somewhere sane. */
-	smp_read_barrier_depends();
-
 	if (!sd) {
 		populate_seccomp_data(&sd_local);
 		sd = &sd_local;
-- 
1.9.1

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