From 1e2b7e53acae1e48457df02566d8bcc97a9b3ab7 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 19 Feb 2019 16:59:15 +0100 Subject: [PATCH 184/291] hrtimer: Don't lose state in cpu_chill() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.90-rt35.tar.xz In cpu_chill() the state is set to TASK_UNINTERRUPTIBLE and a timer is programmed. On return the state is always TASK_RUNNING which means we lose the state if it was something other than RUNNING. Also set_current_state() sets ->task_state_change to within cpu_chill() which is not expected. Save the task state on entry and restore it on return. Simply set the state in order to avoid updating ->task_state_change. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- kernel/time/hrtimer.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 851b2134e77f..6f2736ec4b8e 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -1902,15 +1902,18 @@ void cpu_chill(void) { ktime_t chill_time; unsigned int freeze_flag = current->flags & PF_NOFREEZE; + long saved_state; + saved_state = current->state; chill_time = ktime_set(0, NSEC_PER_MSEC); - set_current_state(TASK_UNINTERRUPTIBLE); + __set_current_state_no_track(TASK_UNINTERRUPTIBLE); current->flags |= PF_NOFREEZE; sleeping_lock_inc(); schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD); sleeping_lock_dec(); if (!freeze_flag) current->flags &= ~PF_NOFREEZE; + __set_current_state_no_track(saved_state); } EXPORT_SYMBOL(cpu_chill); #endif -- 2.24.0