54 lines
2.3 KiB
Diff
54 lines
2.3 KiB
Diff
From 113b6618daafc3b405c7a605deaca3ece1dde64a Mon Sep 17 00:00:00 2001
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Message-Id: <113b6618daafc3b405c7a605deaca3ece1dde64a.1601675151.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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 3 Jul 2018 18:19:48 +0200
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Subject: [PATCH 014/333] cgroup: use irqsave in cgroup_rstat_flush_locked()
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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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All callers of cgroup_rstat_flush_locked() acquire cgroup_rstat_lock
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either with spin_lock_irq() or spin_lock_irqsave().
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cgroup_rstat_flush_locked() itself acquires cgroup_rstat_cpu_lock which
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is a raw_spin_lock. This lock is also acquired in cgroup_rstat_updated()
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in IRQ context and therefore requires _irqsave() locking suffix in
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cgroup_rstat_flush_locked().
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Since there is no difference between spin_lock_t and raw_spin_lock_t
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on !RT lockdep does not complain here. On RT lockdep complains because
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the interrupts were not disabled here and a deadlock is possible.
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Acquire the raw_spin_lock_t with disabled interrupts.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/cgroup/rstat.c | 5 +++--
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1 file changed, 3 insertions(+), 2 deletions(-)
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diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
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index d0ed410b4127..3c949c46c6b3 100644
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--- a/kernel/cgroup/rstat.c
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+++ b/kernel/cgroup/rstat.c
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@@ -149,8 +149,9 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
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raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
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cpu);
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struct cgroup *pos = NULL;
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+ unsigned long flags;
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- raw_spin_lock(cpu_lock);
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+ raw_spin_lock_irqsave(cpu_lock, flags);
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while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
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struct cgroup_subsys_state *css;
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@@ -162,7 +163,7 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
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css->ss->css_rstat_flush(css, cpu);
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rcu_read_unlock();
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}
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- raw_spin_unlock(cpu_lock);
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+ raw_spin_unlock_irqrestore(cpu_lock, flags);
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/* if @may_sleep, play nice and yield if necessary */
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if (may_sleep && (need_resched() ||
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--
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2.17.1
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