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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2015-05-11 17:52:17 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-19 08:39:17 +0200
commit2f09b227eeed4b3a072fe818c82a4c773b778cde (patch)
tree116873485fa5f52844cf1703d291ab5321f218af /arch/arm64/include/asm/futex.h
parentsched/preempt, arm/futex: Disable preemption in UP futex_atomic_op_inuser() explicitly (diff)
downloadlinux-dev-2f09b227eeed4b3a072fe818c82a4c773b778cde.tar.xz
linux-dev-2f09b227eeed4b3a072fe818c82a4c773b778cde.zip
sched/preempt, futex: Update comments to clarify that preemption doesn't have to be disabled
As arm64 and arc have no special implementations for !CONFIG_SMP, mutual exclusion doesn't seem to rely on preemption. Let's make it clear in the comments that preemption doesn't have to be disabled when accessing user space in the futex code, so we can remove preempt_disable() from pagefault_disable(). Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-13-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to '')
-rw-r--r--arch/arm64/include/asm/futex.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
index 5f750dc96e0f..74069b3bd919 100644
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -58,7 +58,7 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
- pagefault_disable(); /* implies preempt_disable() */
+ pagefault_disable();
switch (op) {
case FUTEX_OP_SET:
@@ -85,7 +85,7 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
ret = -ENOSYS;
}
- pagefault_enable(); /* subsumes preempt_enable() */
+ pagefault_enable();
if (!ret) {
switch (cmp) {