From: Nicolas Pitre <nicolas.pitre@linaro.org>
Date: Wed, 12 Aug 2015 15:45:02 +0000 (+0100)
Subject: ARM: 8414/1: __copy_to_user_memcpy: fix mmap semaphore usage
X-Git-Tag: v4.2-rc8~4^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0f64b247e63ac8c214efa6725366b42563ab138c;p=profile%2Fcommon%2Fplatform%2Fkernel%2Flinux-artik7.git

ARM: 8414/1: __copy_to_user_memcpy: fix mmap semaphore usage

The mmap semaphore should not be taken when page faults are disabled.
Since pagefault_disable() no longer disables preemption, we now need
to use faulthandler_disabled() in place of in_atomic().

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/lib/uaccess_with_memcpy.c b/arch/arm/lib/uaccess_with_memcpy.c
index 3e58d71..4b39af2 100644
--- a/arch/arm/lib/uaccess_with_memcpy.c
+++ b/arch/arm/lib/uaccess_with_memcpy.c
@@ -96,7 +96,7 @@ __copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
 	}
 
 	/* the mmap semaphore is taken only if not in an atomic context */
-	atomic = in_atomic();
+	atomic = faulthandler_disabled();
 
 	if (!atomic)
 		down_read(&current->mm->mmap_sem);