From c94eee1a9ae1745a805eeb2d8d218b0c2c8dba2f Mon Sep 17 00:00:00 2001
Message-Id: <c94eee1a9ae1745a805eeb2d8d218b0c2c8dba2f.1594742966.git.zanussi@kernel.org>
In-Reply-To: <832f7d97d6b989a5b4860dd2dbec58ad6ad5ab81.1594742966.git.zanussi@kernel.org>
References: <832f7d97d6b989a5b4860dd2dbec58ad6ad5ab81.1594742966.git.zanussi@kernel.org>
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 18 Feb 2019 16:57:09 +0100
Subject: [PATCH 240/329] x86: lazy-preempt: properly check against
 preempt-mask
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.132-rt59.tar.xz

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 <bigeasy@linutronix.de>
---
 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;
-- 
2.17.1

