57 lines
1.9 KiB
Diff
57 lines
1.9 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 26 Feb 2019 12:31:10 +0100
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Subject: [PATCH] hrtimer: cpu_chill(): save task state in ->saved_state()
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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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In the previous change I saved the current task state on stack. This was
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bad because while the task is scheduled-out it might receive a wake-up.
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The wake up changes the task state and we must not destroy it.
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Save the task-state in ->saved_state under a PI-lock to unsure that
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state changes during are not missed while the task temporary scheduled
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out.
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Reported-by: Mike Galbraith <efault@gmx.de>
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Tested-by: Mike Galbraith <efault@gmx.de>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/time/hrtimer.c | 18 +++++++++++++-----
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1 file changed, 13 insertions(+), 5 deletions(-)
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--- a/kernel/time/hrtimer.c
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+++ b/kernel/time/hrtimer.c
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@@ -1900,20 +1900,28 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct
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*/
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void cpu_chill(void)
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{
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- ktime_t chill_time;
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unsigned int freeze_flag = current->flags & PF_NOFREEZE;
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- long saved_state;
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+ struct task_struct *self = current;
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+ ktime_t chill_time;
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- saved_state = current->state;
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- chill_time = ktime_set(0, NSEC_PER_MSEC);
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+ raw_spin_lock_irq(&self->pi_lock);
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+ self->saved_state = self->state;
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__set_current_state_no_track(TASK_UNINTERRUPTIBLE);
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+ raw_spin_unlock_irq(&self->pi_lock);
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+
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+ chill_time = ktime_set(0, NSEC_PER_MSEC);
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+
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current->flags |= PF_NOFREEZE;
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sleeping_lock_inc();
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schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD);
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sleeping_lock_dec();
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if (!freeze_flag)
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current->flags &= ~PF_NOFREEZE;
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- __set_current_state_no_track(saved_state);
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+
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+ raw_spin_lock_irq(&self->pi_lock);
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+ __set_current_state_no_track(self->saved_state);
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+ self->saved_state = TASK_RUNNING;
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+ raw_spin_unlock_irq(&self->pi_lock);
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}
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EXPORT_SYMBOL(cpu_chill);
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#endif
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