46 lines
1.9 KiB
Diff
46 lines
1.9 KiB
Diff
From 6c5cfa0b2bf6c2aee38e6fe0d3ea198eeda6332f Mon Sep 17 00:00:00 2001
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Message-Id: <6c5cfa0b2bf6c2aee38e6fe0d3ea198eeda6332f.1596234184.git.zanussi@kernel.org>
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In-Reply-To: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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References: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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From: Julien Grall <julien.grall@arm.com>
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Date: Wed, 21 Aug 2019 10:24:07 +0100
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Subject: [PATCH 293/329] hrtimer: Use READ_ONCE to access timer->base in
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hrimer_grab_expiry_lock()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.135-rt60.tar.xz
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[ Upstream commit 2c8fdbe7ef0ad06c1a326886c5954e117b5657d6 ]
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The update to timer->base is protected by the base->cpu_base->lock().
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However, hrtimer_grab_expirty_lock() does not access it with the lock.
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So it would theorically be possible to have timer->base changed under
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our feet. We need to prevent the compiler to refetch timer->base so the
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check and the access is performed on the same base.
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Other access of timer->base are either done with a lock or protected
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with READ_ONCE(). So use READ_ONCE() in hrtimer_grab_expirty_lock().
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Signed-off-by: Julien Grall <julien.grall@arm.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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---
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kernel/time/hrtimer.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
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index 94d97eae0a46..d6026c170c2d 100644
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--- a/kernel/time/hrtimer.c
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+++ b/kernel/time/hrtimer.c
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@@ -941,7 +941,7 @@ EXPORT_SYMBOL_GPL(hrtimer_forward);
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void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
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{
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- struct hrtimer_clock_base *base = timer->base;
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+ struct hrtimer_clock_base *base = READ_ONCE(timer->base);
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if (base && base->cpu_base) {
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spin_lock(&base->cpu_base->softirq_expiry_lock);
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--
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2.17.1
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