Commit-ID: f3dae07e442a8131a5485b6a38db2aa22a7a48cf Gitweb: http://git.kernel.org/tip/f3dae07e442a8131a5485b6a38db2aa22a7a48cf Author: David Hildenbrand <[email protected]> AuthorDate: Mon, 11 May 2015 17:52:13 +0200 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Signed-off-by: David Hildenbrand <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
