kernel/linux.git/sound/core/hrtimer.c, branch v6.6.131

ALSA: timer: Replace tasklet with work

2020-09-09T16:32:52+00:00

The tasklet is an old API that should be deprecated, usually can be converted to another decent API. In ALSA core timer API, the callbacks can be offlined to a tasklet when a flag is set in the timer backend. It can be achieved gracefully with a work queued in the high-prio system workqueue. This patch replaces the usage of tasklet in ALSA timer API with a simple work. Currently the tasklet feature is used only in the system timer and hrtimer backends, so both are patched to use the new flag name SNDRV_TIMER_HW_WORK, too. Link: https://lore.kernel.org/r/20200903104131.21097-3-tiwai@suse.de Signed-off-by: Takashi Iwai

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-next' into for-linus

2017-11-13T14:43:13+00:00

Pull 4.15 updates to take over the previous urgent fixes. Signed-off-by: Takashi Iwai

ALSA: timer: Limit max instances per timer

2017-11-06T09:41:24+00:00

Currently we allow unlimited number of timer instances, and it may bring the system hogging way too much CPU when too many timer instances are opened and processed concurrently. This may end up with a soft-lockup report as triggered by syzkaller, especially when hrtimer backend is deployed. Since such insane number of instances aren't demanded by the normal use case of ALSA sequencer and it merely opens a risk only for abuse, this patch introduces the upper limit for the number of instances per timer backend. As default, it's set to 1000, but for the fine-grained timer like hrtimer, it's set to 100. Reported-by: syzbot Tested-by: Jérôme Glisse Cc: Signed-off-by: Takashi Iwai

ALSA: hrtimer: make hrtimer_hw const and __initconst

2017-09-19T20:06:11+00:00

Make this const as it is only used during a copy operation. Also, make it __initconst as it is only used during the init phase and after this it is not referenced anywhere. Signed-off-by: Bhumika Goyal Signed-off-by: Takashi Iwai

ktime: Get rid of the union

2016-12-25T16:21:22+00:00

ktime is a union because the initial implementation stored the time in scalar nanoseconds on 64 bit machine and in a endianess optimized timespec variant for 32bit machines. The Y2038 cleanup removed the timespec variant and switched everything to scalar nanoseconds. The union remained, but become completely pointless. Get rid of the union and just keep ktime_t as simple typedef of type s64. The conversion was done with coccinelle and some manual mopping up. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra

ALSA: hrtimer: Handle start/stop more properly

2016-04-26T07:34:40+00:00

This patch tries to address the still remaining issues in ALSA hrtimer driver: - Spurious use-after-free was detected in hrtimer callback - Incorrect rescheduling due to delayed start - WARN_ON() is triggered in hrtimer_forward() invoked in hrtimer callback The first issue happens only when the new timer is scheduled even while hrtimer is being closed. It's related with the second and third items; since ALSA timer core invokes hw.start callback during hrtimer interrupt, this may result in the explicit call of hrtimer_start(). Also, the similar problem is seen for the stop; ALSA timer core invokes hw.stop callback even in the hrtimer handler, too. Since we must not call the synced hrtimer_cancel() in such a context, it's just a hrtimer_try_to_cancel() call that doesn't properly work. Another culprit of the second and third items is the call of hrtimer_forward_now() before snd_timer_interrupt(). The timer->stick value may change during snd_timer_interrupt() call, but this possibility is ignored completely. For covering these subtle and messy issues, the following changes have been done in this patch: - A new flag, in_callback, is introduced in the private data to indicate that the hrtimer handler is being processed. - Both start and stop callbacks skip when called from (during) in_callback flag. - The hrtimer handler returns properly HRTIMER_RESTART and NORESTART depending on the running state now. - The hrtimer handler reprograms the expiry properly after snd_timer_interrupt() call, instead of before. - The close callback clears running flag and sets in_callback flag to block any further start/stop calls. Signed-off-by: Takashi Iwai

ALSA: hrtimer: Fix stall by hrtimer_cancel()

2016-01-18T13:33:30+00:00

hrtimer_cancel() waits for the completion from the callback, thus it must not be called inside the callback itself. This was already a problem in the past with ALSA hrtimer driver, and the early commit [fcfdebe70759: ALSA: hrtimer - Fix lock-up] tried to address it. However, the previous fix is still insufficient: it may still cause a lockup when the ALSA timer instance reprograms itself in its callback. Then it invokes the start function even in snd_timer_interrupt() that is called in hrtimer callback itself, results in a CPU stall. This is no hypothetical problem but actually triggered by syzkaller fuzzer. This patch tries to fix the issue again. Now we call hrtimer_try_to_cancel() at both start and stop functions so that it won't fall into a deadlock, yet giving some chance to cancel the queue if the functions have been called outside the callback. The proper hrtimer_cancel() is called in anyway at closing, so this should be enough. Reported-and-tested-by: Dmitry Vyukov Cc: Signed-off-by: Takashi Iwai

sound: Use hrtimer_resolution instead of hrtimer_get_res()

2015-04-22T15:06:48+00:00

No point in converting a timespec now that the value is directly accessible. Get rid of the null check while at it. Resolution is guaranteed to be > 0. Signed-off-by: Thomas Gleixner Acked-by: Takashi Iwai Acked-by: Peter Zijlstra Cc: Preeti U Murthy Cc: Viresh Kumar Cc: Marcelo Tosatti Cc: Frederic Weisbecker Cc: Jaroslav Kysela Cc: alsa-devel@alsa-project.org Link: http://lkml.kernel.org/r/20150414203500.799133359@linutronix.de Signed-off-by: Thomas Gleixner

ALSA: timer: Use standard printk helpers

2014-02-14T07:14:17+00:00

Use the standard pr_xxx() helpers instead of home-baked snd_print*(). Signed-off-by: Takashi Iwai