56 lines
1.6 KiB
Diff
56 lines
1.6 KiB
Diff
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From cd0526cfcc2221b6bebc0f0c7833bb86ba39f114 Mon Sep 17 00:00:00 2001
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From: Tiejun Chen <tiejun.chen@windriver.com>
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Date: Wed, 18 Dec 2013 17:51:49 +0800
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Subject: [PATCH 186/365] rcutree/rcu_bh_qs: Disable irq while calling
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rcu_preempt_qs()
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Any callers to the function rcu_preempt_qs() must disable irqs in
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order to protect the assignment to ->rcu_read_unlock_special. In
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RT case, rcu_bh_qs() as the wrapper of rcu_preempt_qs() is called
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in some scenarios where irq is enabled, like this path,
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do_single_softirq()
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+ local_irq_enable();
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+ handle_softirq()
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| + rcu_bh_qs()
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| + rcu_preempt_qs()
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+ local_irq_disable()
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So here we'd better disable irq directly inside of rcu_bh_qs() to
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fix this, otherwise the kernel may be freezable sometimes as
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observed. And especially this way is also kind and safe for the
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potential rcu_bh_qs() usage elsewhere in the future.
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Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
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Signed-off-by: Bin Jiang <bin.jiang@windriver.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/rcu/tree.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
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index 6d8eca89b239..b627ee1e4669 100644
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--- a/kernel/rcu/tree.c
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+++ b/kernel/rcu/tree.c
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@@ -265,7 +265,12 @@ static void rcu_preempt_qs(void);
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void rcu_bh_qs(void)
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{
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+ unsigned long flags;
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+
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+ /* Callers to this function, rcu_preempt_qs(), must disable irqs. */
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+ local_irq_save(flags);
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rcu_preempt_qs();
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+ local_irq_restore(flags);
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}
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#else
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void rcu_bh_qs(void)
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--
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2.28.0
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