54 lines
2.2 KiB
Diff
54 lines
2.2 KiB
Diff
From e7610b6d4601c96dcc59dee0a8c14e26256b65e5 Mon Sep 17 00:00:00 2001
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Message-Id: <e7610b6d4601c96dcc59dee0a8c14e26256b65e5.1601675153.git.zanussi@kernel.org>
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In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
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Date: Tue, 28 Apr 2020 16:40:26 +0200
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Subject: [PATCH 325/333] hrtimer: fix logic for when grabbing
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softirq_expiry_lock can be elided
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz
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Commit
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hrtimer: Add a missing bracket and hide `migration_base' on !SMP
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which is 47b6de0b7f22 in 5.2-rt and 40aae5708e7a in 4.19-rt,
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inadvertently changed the logic from base != &migration_base to base
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== &migration_base.
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On !CONFIG_SMP, the effect was to effectively always elide this
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lock/unlock pair (since is_migration_base() is unconditionally false),
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which for me consistently causes lockups during reboot, and reportedly
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also often causes a hang during boot.
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Adding this logical negation (or, what is effectively the same thing
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on !CONFIG_SMP, reverting the above commit as well as "hrtimer:
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Prevent using hrtimer_grab_expiry_lock() on migration_base") fixes
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that lockup.
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Fixes: 40aae5708e7a (hrtimer: Add a missing bracket and hide `migration_base' on !SMP) # 4.19-rt
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Fixes: 47b6de0b7f22 (hrtimer: Add a missing bracket and hide `migration_base' on !SMP) # 5.2-rt
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Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
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Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Signed-off-by: Tom Zanussi <zanussi@kernel.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 e54a95de8b79..c3966c090246 100644
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--- a/kernel/time/hrtimer.c
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+++ b/kernel/time/hrtimer.c
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@@ -953,7 +953,7 @@ void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
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{
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struct hrtimer_clock_base *base = READ_ONCE(timer->base);
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- if (timer->is_soft && is_migration_base(base)) {
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+ if (timer->is_soft && !is_migration_base(base)) {
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spin_lock(&base->cpu_base->softirq_expiry_lock);
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spin_unlock(&base->cpu_base->softirq_expiry_lock);
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}
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--
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2.17.1
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