locking/barriers: Convert users of lockless_dereference() to READ_ONCE()
commit 3382290ed2d5e275429cef510ab21889d3ccd164 upstream.
[ Note, this is a Git cherry-pick of the following commit:
506458efaf15 ("locking/barriers: Convert users of lockless_dereference() to READ_ONCE()")
... for easier x86 PTI code testing and back-porting. ]
READ_ONCE() now has an implicit smp_read_barrier_depends() call, so it
can be used instead of lockless_dereference() without any change in
semantics.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-4-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 418a1c0..5f0dfb2ab 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -190,7 +190,7 @@
u32 ret = SECCOMP_RET_ALLOW;
/* Make sure cross-thread synced filter points somewhere sane. */
struct seccomp_filter *f =
- lockless_dereference(current->seccomp.filter);
+ READ_ONCE(current->seccomp.filter);
/* Ensure unexpected behavior doesn't result in failing open. */
if (unlikely(WARN_ON(f == NULL)))