75 lines
1.9 KiB
Diff
75 lines
1.9 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 20 Jan 2016 15:13:30 +0100
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Subject: preempt-lazy: Add the lazy-preemption check to preempt_schedule()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.6/older/patches-4.6.2-rt5.tar.xz
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Probably in the rebase onto v4.1 this check got moved into less commonly used
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preempt_schedule_notrace(). This patch ensures that both functions use it.
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Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/sched/core.c | 36 ++++++++++++++++++++++++++++--------
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1 file changed, 28 insertions(+), 8 deletions(-)
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -3500,6 +3500,30 @@ static void __sched notrace preempt_sche
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} while (need_resched());
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}
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+#ifdef CONFIG_PREEMPT_LAZY
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+/*
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+ * If TIF_NEED_RESCHED is then we allow to be scheduled away since this is
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+ * set by a RT task. Oterwise we try to avoid beeing scheduled out as long as
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+ * preempt_lazy_count counter >0.
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+ */
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+static __always_inline int preemptible_lazy(void)
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+{
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+ if (test_thread_flag(TIF_NEED_RESCHED))
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+ return 1;
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+ if (current_thread_info()->preempt_lazy_count)
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+ return 0;
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+ return 1;
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+}
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+
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+#else
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+
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+static int preemptible_lazy(void)
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+{
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+ return 1;
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+}
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+
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+#endif
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+
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#ifdef CONFIG_PREEMPT
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/*
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* this is the entry point to schedule() from in-kernel preemption
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@@ -3514,6 +3538,8 @@ asmlinkage __visible void __sched notrac
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*/
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if (likely(!preemptible()))
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return;
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+ if (!preemptible_lazy())
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+ return;
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preempt_schedule_common();
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}
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@@ -3540,15 +3566,9 @@ asmlinkage __visible void __sched notrac
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if (likely(!preemptible()))
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return;
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-
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-#ifdef CONFIG_PREEMPT_LAZY
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- /*
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- * Check for lazy preemption
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- */
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- if (current_thread_info()->preempt_lazy_count &&
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- !test_thread_flag(TIF_NEED_RESCHED))
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+ if (!preemptible_lazy())
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return;
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-#endif
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+
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do {
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preempt_disable_notrace();
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/*
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