116 lines
3.6 KiB
Diff
116 lines
3.6 KiB
Diff
From 4896dd79dae04b0e05c498f65d29484e736ec6d9 Mon Sep 17 00:00:00 2001
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Message-Id: <4896dd79dae04b0e05c498f65d29484e736ec6d9.1601675152.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: Mon, 18 Feb 2019 13:19:59 +0100
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Subject: [PATCH 125/333] softirq: Avoid "local_softirq_pending" messages if
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ksoftirqd is blocked
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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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If the ksoftirqd thread has a softirq pending and is blocked on the
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`local_softirq_locks' lock then softirq_check_pending_idle() won't
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complain because the "lock owner" will mask away this softirq from the
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mask of pending softirqs.
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If ksoftirqd has an additional softirq pending then it won't be masked
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out because we never look at ksoftirqd's mask.
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If there are still pending softirqs while going to idle check
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ksoftirqd's and ktimersfotd's mask before complaining about unhandled
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softirqs.
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Cc: stable-rt@vger.kernel.org
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Tested-by: Juri Lelli <juri.lelli@redhat.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/softirq.c | 57 ++++++++++++++++++++++++++++++++++--------------
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1 file changed, 41 insertions(+), 16 deletions(-)
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diff --git a/kernel/softirq.c b/kernel/softirq.c
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index fe4e59c80a08..1920985eeb09 100644
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--- a/kernel/softirq.c
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+++ b/kernel/softirq.c
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@@ -92,6 +92,31 @@ static inline void softirq_clr_runner(unsigned int sirq)
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sr->runner[sirq] = NULL;
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}
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+static bool softirq_check_runner_tsk(struct task_struct *tsk,
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+ unsigned int *pending)
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+{
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+ bool ret = false;
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+
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+ if (!tsk)
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+ return ret;
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+
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+ /*
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+ * The wakeup code in rtmutex.c wakes up the task
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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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+ */
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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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+ /* 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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+ }
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+ raw_spin_unlock(&tsk->pi_lock);
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+
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+ return ret;
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+}
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+
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/*
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* On preempt-rt a softirq running context might be blocked on a
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* lock. There might be no other runnable task on this CPU because the
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@@ -104,6 +129,7 @@ static inline void softirq_clr_runner(unsigned int sirq)
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*/
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void softirq_check_pending_idle(void)
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{
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+ struct task_struct *tsk;
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static int rate_limit;
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struct softirq_runner *sr = this_cpu_ptr(&softirq_runners);
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u32 warnpending;
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@@ -113,24 +139,23 @@ void softirq_check_pending_idle(void)
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return;
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warnpending = local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK;
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+ if (!warnpending)
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+ return;
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for (i = 0; i < NR_SOFTIRQS; i++) {
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- struct task_struct *tsk = sr->runner[i];
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+ tsk = sr->runner[i];
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- /*
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- * The wakeup code in rtmutex.c wakes up the task
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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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- */
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- if (tsk) {
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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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- /* Clear all bits pending in that task */
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- warnpending &= ~(tsk->softirqs_raised);
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- warnpending &= ~(1 << i);
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- }
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- raw_spin_unlock(&tsk->pi_lock);
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- }
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+ if (softirq_check_runner_tsk(tsk, &warnpending))
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+ warnpending &= ~(1 << i);
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+ }
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+
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+ if (warnpending) {
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+ tsk = __this_cpu_read(ksoftirqd);
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+ softirq_check_runner_tsk(tsk, &warnpending);
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+ }
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+
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+ if (warnpending) {
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+ tsk = __this_cpu_read(ktimer_softirqd);
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+ softirq_check_runner_tsk(tsk, &warnpending);
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}
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if (warnpending) {
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--
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2.17.1
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