36 lines
1.4 KiB
Diff
36 lines
1.4 KiB
Diff
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 19 Feb 2019 16:49:29 +0100
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Subject: [PATCH] softirq: Avoid "local_softirq_pending" messages if task
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is in cpu_chill()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.25-rt16.tar.xz
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If the softirq thread enters cpu_chill() then ->state is UNINTERRUPTIBLE
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and has no ->pi_blocked_on set and so its mask is not taken into account.
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->sleeping_lock is increased by cpu_chill() since it is also requried to
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avoid a splat by RCU in case cpu_chill() is used while a RCU-read lock
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is held. Use the same mechanism for the softirq-pending check.
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Cc: stable-rt@vger.kernel.org
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/softirq.c | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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--- a/kernel/softirq.c
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+++ b/kernel/softirq.c
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@@ -105,9 +105,12 @@ static bool softirq_check_runner_tsk(str
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* _before_ it sets pi_blocked_on to NULL under
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* tsk->pi_lock. So we need to check for both: state
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* and pi_blocked_on.
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+ * The test against UNINTERRUPTIBLE + ->sleeping_lock is in case the
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+ * task does cpu_chill().
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*/
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raw_spin_lock(&tsk->pi_lock);
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- if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING) {
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+ if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING ||
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+ (tsk->state == TASK_UNINTERRUPTIBLE && tsk->sleeping_lock)) {
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/* Clear all bits pending in that task */
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*pending &= ~(tsk->softirqs_raised);
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ret = true;
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