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Subject[tip:core/futexes] futex: Remove redundant pagefault_disable in futex_atomic_cmpxchg_inatomic()
Commit-ID:  522d7decc0370070448a8c28982c8dfd8970489e
Gitweb: http://git.kernel.org/tip/522d7decc0370070448a8c28982c8dfd8970489e
Author: Michel Lespinasse <walken@google.com>
AuthorDate: Thu, 10 Mar 2011 18:47:31 -0800
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 11 Mar 2011 12:23:08 +0100

futex: Remove redundant pagefault_disable in futex_atomic_cmpxchg_inatomic()

kernel/futex.c disables page faults before calling
futex_atomic_cmpxchg_inatomic(), so there is no need to do it again
within that function.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110311024731.GB26122@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
arch/arm/include/asm/futex.h | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index b33fe70..7133a86 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -95,7 +95,8 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
return -EFAULT;

- pagefault_disable(); /* implies preempt_disable() */
+ /* Note that preemption is disabled by futex_atomic_cmpxchg_inatomic
+ * call sites. */

__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
"1: " T(ldr) " %0, [%3]\n"
@@ -115,8 +116,6 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
: "cc", "memory");

- pagefault_enable(); /* subsumes preempt_enable() */
-
return val;
}


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