Messages in this thread Patch in this message | | | Date | Tue, 19 May 2015 00:20:45 -0700 | From | tip-bot for David Hildenbrand <> | Subject | [tip:sched/core] sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly |
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Commit-ID: d9b9ff8c18891d74dc7076800bde81b774f7d032 Gitweb: http://git.kernel.org/tip/d9b9ff8c18891d74dc7076800bde81b774f7d032 Author: David Hildenbrand <dahi@linux.vnet.ibm.com> AuthorDate: Mon, 11 May 2015 17:52:14 +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_cmpxchg_inatomic() explicitly
Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_cmpxchg_inatomic(), to prepare for pagefault_disable() not touching preemption anymore. This is needed for this function to be callable from both, atomic and non-atomic context.
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/1431359540-32227-10-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- include/asm-generic/futex.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 3586017..e56272c 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -107,6 +107,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, { u32 val; + preempt_disable(); if (unlikely(get_user(val, uaddr) != 0)) return -EFAULT; @@ -114,6 +115,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, return -EFAULT; *uval = val; + preempt_enable(); return 0; }
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