Commit-ID: 39919b01ae4c1949736b40b79e27178d0c0bc406
Gitweb: http://git.kernel.org/tip/39919b01ae4c1949736b40b79e27178d0c0bc406
Author: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 11 May 2015 17:52:15 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 19 May 2015 08:39:16 +0200
sched/preempt, arm/futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly
The !CONFIG_SMP implementation of futex_atomic_cmpxchg_inatomic()
requires preemption to be disabled to guarantee mutual exclusion.
Let's make this explicit.
This patch is based on a patch by Sebastian Andrzej Siewior on the
-rt branch.
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/1431359540-32227-11-git-send-email-dahi@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/arm/include/asm/futex.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 4e78065..255bfd1 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -93,6 +93,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
+ preempt_disable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
"1: " TUSER(ldr) " %1, [%4]\n"
" teq %1, %2\n"
@@ -104,6 +105,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
: "cc", "memory");
*uval = val;
+ preempt_enable();
+
return ret;
}
--
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