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 <d...@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Michel Lespinasse <wal...@google.com>
Signed-off-by: Vineet Gupta <vgu...@synopsys.com>
---
arch/arc/include/asm/futex.h | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
index 70cfe16b742d..9de18a526aff 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
@@ -134,13 +138,8 @@ static inline int futex_atomic_op_inuser(int encoded_op,
u32 __user *uaddr)
return ret;
}
-/* Compare-xchg with pagefaults disabled.
- * Notes:
- * -Best-Effort: Exchg happens only if compare succeeds.
- * If compare fails, returns; leaving retry/looping to upper layers
- * -successful cmp-xchg: return orig value in @addr (same as cmp val)
- * -Compare fails: return orig value in @addr
- * -user access r/w fails: return -EFAULT
+/*
+ * cmpxchg of futex (pagefaults disabled by caller)
*/
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
@@ -151,7 +150,7 @@ 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 +177,7 @@ 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
