Messages in this thread Patch in this message | | | Date | Thu, 21 Apr 2016 03:07:01 -0700 | From | tip-bot for Romain Perier <> | Subject | [tip:locking/urgent] asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic() |
| |
Commit-ID: fba7cd681b6155e2d93e7862fcd6f970336b83c3 Gitweb: http://git.kernel.org/tip/fba7cd681b6155e2d93e7862fcd6f970336b83c3 Author: Romain Perier <romain.perier@free-electrons.com> AuthorDate: Thu, 14 Apr 2016 15:36:03 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Thu, 21 Apr 2016 11:06:09 +0200
asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic()
The recent decoupling of pagefault disable and preempt disable added an explicit preempt_disable/enable() pair to the futex_atomic_cmpxchg_inatomic() implementation in asm-generic/futex.h. But it forgot to add preempt_enable() calls to the error handling code pathes, which results in a preemption count imbalance.
This is observable on boot when the test for atomic_cmpxchg() is calling futex_atomic_cmpxchg_inatomic() on a NULL pointer.
Add the missing preempt_enable() calls to the error handling code pathes.
[ tglx: Massaged changelog ]
Fixes: d9b9ff8c1889 ("sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly") Signed-off-by: Romain Perier <romain.perier@free-electrons.com> Cc: linux-arch@vger.kernel.org Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1460640963-690-1-git-send-email-romain.perier@free-electrons.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/asm-generic/futex.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index e56272c..bf2d34c 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -108,11 +108,15 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 val; preempt_disable(); - if (unlikely(get_user(val, uaddr) != 0)) + if (unlikely(get_user(val, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } - if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) + if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } *uval = val; preempt_enable();
| |