From: Sebastian Andrzej Siewior Date: Mon, 18 Feb 2019 16:57:09 +0100 Subject: [PATCH 239/353] x86: lazy-preempt: properly check against preempt-mask Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=265f0d10b439e19e1d0e42602626bfbc315b798c should_resched() should check against preempt_offset after unmasking the need-resched-bit. Otherwise should_resched() won't work for preempt_offset != 0 and lazy-preempt set. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/include/asm/preempt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 22992c837795..f66708779274 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -118,7 +118,7 @@ static __always_inline bool should_resched(int preempt_offset) /* preempt count == 0 ? */ tmp &= ~PREEMPT_NEED_RESCHED; - if (tmp) + if (tmp != preempt_offset) return false; if (current_thread_info()->preempt_lazy_count) return false;