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Subject[PATCH 1/4] ARC: add barriers to futex code
Date
The atomic ops on futex need to provide the full barrier just like
regular atomics in kernel.

Also remove pagefault_enable/disable in futex_atomic_cmpxchg_inatomic()
as core code already does that

Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/futex.h | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
index 70cfe16b742d..160656d0a15a 100644
--- a/arch/arc/include/asm/futex.h
+++ b/arch/arc/include/asm/futex.h
@@ -20,6 +20,7 @@

#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
\
+ smp_mb(); \
__asm__ __volatile__( \
"1: llock %1, [%2] \n" \
insn "\n" \
@@ -40,12 +41,14 @@
\
: "=&r" (ret), "=&r" (oldval) \
: "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
- : "cc", "memory")
+ : "cc", "memory"); \
+ smp_mb(); \

#else /* !CONFIG_ARC_HAS_LLSC */

#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
\
+ smp_mb(); \
__asm__ __volatile__( \
"1: ld %1, [%2] \n" \
insn "\n" \
@@ -65,7 +68,8 @@
\
: "=&r" (ret), "=&r" (oldval) \
: "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
- : "cc", "memory")
+ : "cc", "memory"); \
+ smp_mb(); \

#endif

@@ -151,7 +155,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
return -EFAULT;

- pagefault_disable();
+ smp_mb();

__asm__ __volatile__(
#ifdef CONFIG_ARC_HAS_LLSC
@@ -178,7 +182,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
: "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
: "cc", "memory");

- pagefault_enable();
+ smp_mb();

*uval = val;
return val;
--
1.9.1


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