Messages in this thread Patch in this message | | | Date | Tue, 19 May 2015 00:20:26 -0700 | From | tip-bot for David Hildenbrand <> | Subject | [tip:sched/core] sched/preempt, futex: Disable preemption in UP futex_atomic_op_inuser() explicitly |
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Commit-ID: f3dae07e442a8131a5485b6a38db2aa22a7a48cf Gitweb: http://git.kernel.org/tip/f3dae07e442a8131a5485b6a38db2aa22a7a48cf Author: David Hildenbrand <dahi@linux.vnet.ibm.com> AuthorDate: Mon, 11 May 2015 17:52:13 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 19 May 2015 08:39:16 +0200
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> --- include/asm-generic/futex.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index b59b5a5..3586017 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) {
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