linux/debian/patches-rt/0240-x86-lazy-preempt-prope...

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From 148cdab3ace63f2ec560f4aa496a0910e85cac12 Mon Sep 17 00:00:00 2001
Message-Id: <148cdab3ace63f2ec560f4aa496a0910e85cac12.1601675152.git.zanussi@kernel.org>
In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 18 Feb 2019 16:57:09 +0100
Subject: [PATCH 240/333] x86: lazy-preempt: properly check against
preempt-mask
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.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