Messages in this thread Patch in this message | | | Date | Tue, 19 May 2015 00:21:05 -0700 | From | tip-bot for David Hildenbrand <> | Subject | [tip:sched/core] sched/preempt, arm/futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly |
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Commit-ID: 39919b01ae4c1949736b40b79e27178d0c0bc406 Gitweb: http://git.kernel.org/tip/39919b01ae4c1949736b40b79e27178d0c0bc406 Author: David Hildenbrand <dahi@linux.vnet.ibm.com> AuthorDate: Mon, 11 May 2015 17:52:15 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 19 May 2015 08:39:16 +0200
sched/preempt, arm/futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly
The !CONFIG_SMP implementation of futex_atomic_cmpxchg_inatomic() requires preemption to be disabled to guarantee mutual exclusion. Let's make this explicit.
This patch is based on a patch by Sebastian Andrzej Siewior on the -rt branch.
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/1431359540-32227-11-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/arm/include/asm/futex.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 4e78065..255bfd1 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -93,6 +93,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; + preempt_disable(); __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" "1: " TUSER(ldr) " %1, [%4]\n" " teq %1, %2\n" @@ -104,6 +105,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, : "cc", "memory"); *uval = val; + preempt_enable(); + return ret; }
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