Commit-ID: f3dae07e442a8131a5485b6a38db2aa22a7a48cf
Gitweb: http://git.kernel.org/tip/f3dae07e442a8131a5485b6a38db2aa22a7a48cf
Author: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 11 May 2015 17:52:13 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 19 May 2015 08:39:16 +0200
sched/preempt, futex: Disable preemption in UP futex_atomic_op_inuser() explicitly
Let's explicitly disable/enable preemption in the !CONFIG_SMP version
of futex_atomic_op_inuser, to prepare for pagefault_disable() not
touching preemption anymore.
Otherwise we might break mutual exclusion when relying on a get_user()/
put_user() implementation.
Reviewed-and-tested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: David.Laight@xxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: airlied@xxxxxxxx
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
Cc: benh@xxxxxxxxxxxxxxxxxxx
Cc: bigeasy@xxxxxxxxxxxxx
Cc: borntraeger@xxxxxxxxxx
Cc: daniel.vetter@xxxxxxxxx
Cc: heiko.carstens@xxxxxxxxxx
Cc: herbert@xxxxxxxxxxxxxxxxxxx
Cc: hocko@xxxxxxx
Cc: hughd@xxxxxxxxxx
Cc: mst@xxxxxxxxxx
Cc: paulus@xxxxxxxxx
Cc: ralf@xxxxxxxxxxxxxx
Cc: schwidefsky@xxxxxxxxxx
Cc: yang.shi@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1431359540-32227-9-git-send-email-dahi@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/asm-generic/futex.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h
index b59b5a5..3586017 100644
--- a/include/asm-generic/futex.h
+++ b/include/asm-generic/futex.h
@@ -8,8 +8,7 @@
#ifndef CONFIG_SMP
/*
* The following implementation only for uniprocessor machines.
- * For UP, it's relies on the fact that pagefault_disable() also disables
- * preemption to ensure mutual exclusion.
+ * It relies on preempt_disable() ensuring mutual exclusion.
*
*/
@@ -38,6 +37,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
oparg = 1 << oparg;
+ preempt_disable();
pagefault_disable();
ret = -EFAULT;
@@ -72,6 +72,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
out_pagefault_enable:
pagefault_enable();
+ preempt_enable();
if (ret == 0) {
switch (cmp) {
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|