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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2015-05-11 17:52:13 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-19 08:39:16 +0200
commitf3dae07e442a8131a5485b6a38db2aa22a7a48cf (patch)
tree93ef299661eab70bbdf2dd70eabe093aa1fb66e6 /include/asm-generic/futex.h
parent32d8206725bcf6e3ce7832ac39e61a6ecfd558db (diff)
sched/preempt, futex: Disable preemption in UP futex_atomic_op_inuser() explicitly
Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_op_inuser, to prepare for pagefault_disable() not touching preemption anymore. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. 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/1431359540-32227-9-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic/futex.h')
-rw-r--r--include/asm-generic/futex.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h
index b59b5a52637e..358601750fe7 100644
--- a/include/asm-generic/futex.h
+++ b/include/asm-generic/futex.h
@@ -8,8 +8,7 @@
#ifndef CONFIG_SMP
/*
* The following implementation only for uniprocessor machines.
- * For UP, it's relies on the fact that pagefault_disable() also disables
- * preemption to ensure mutual exclusion.
+ * It relies on preempt_disable() ensuring mutual exclusion.
*
*/
@@ -38,6 +37,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
oparg = 1 << oparg;
+ preempt_disable();
pagefault_disable();
ret = -EFAULT;
@@ -72,6 +72,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
out_pagefault_enable:
pagefault_enable();
+ preempt_enable();
if (ret == 0) {
switch (cmp) {