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path: root/sound/core/hrtimer.c
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2017-11-13Merge branch 'for-next' into for-linusTakashi Iwai
Pull 4.15 updates to take over the previous urgent fixes. Signed-off-by: Takashi Iwai <tiwai@suse.de>
2017-11-06ALSA: timer: Limit max instances per timerTakashi Iwai
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 <jglisse@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2017-09-19ALSA: hrtimer: make hrtimer_hw const and __initconstBhumika Goyal
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 <bhumirks@gmail.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-12-25ktime: Get rid of the unionThomas Gleixner
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 <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
2016-04-26ALSA: hrtimer: Handle start/stop more properlyTakashi Iwai
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 <tiwai@suse.de>
2016-01-18ALSA: hrtimer: Fix stall by hrtimer_cancel()Takashi Iwai
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 <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2015-04-22sound: Use hrtimer_resolution instead of hrtimer_get_res()Thomas Gleixner
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 <tglx@linutronix.de> Acked-by: Takashi Iwai <tiwai@suse.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: alsa-devel@alsa-project.org Link: http://lkml.kernel.org/r/20150414203500.799133359@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-14ALSA: timer: Use standard printk helpersTakashi Iwai
Use the standard pr_xxx() helpers instead of home-baked snd_print*(). Signed-off-by: Takashi Iwai <tiwai@suse.de>
2011-02-10ALSA: hrtimer: remove superfluous tasklet invocationClemens Ladisch
Commit bb758e9637e5ddc removed snd_hrtimer_callback() from the hardware interrupt handler, thus moving it into a tasklet, but did not tell the ALSA timer framework about this, so the timer handling would now be done in the ALSA timer tasklet scheduled from another tasklet. To fix this, add the flag to tell the ALSA timer framework that the timer handler is already being invoked in a tasklet. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2011-02-10ALSA: hrtimer: handle delayed timer interruptsClemens Ladisch
If a timer interrupt was delayed too much, hrtimer_forward_now() will forward the timer expiry more than once. When this happens, the additional number of elapsed ALSA timer ticks must be passed to snd_timer_interrupt() to prevent the ALSA timer from falling behind. This mostly fixes MIDI slowdown problems on highly-loaded systems with badly behaved interrupt handlers. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Reported-and-tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2010-03-30include cleanup: Update gfp.h and slab.h includes to prepare for breaking ↵Tejun Heo
implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2009-12-11ALSA: hrtimer - Fix lock-upTakashi Iwai
The timer stop callback can be called from snd_timer_interrupt(), which is called from the hrtimer callback. Since hrtimer_cancel() waits for the callback completion, this eventually results in a lock-up. This patch fixes the problem by just toggling a flag at stop callback and call hrtimer_cancel() later. Reported-and-tested-by: Wojtek Zabolotny <W.Zabolotny@elka.pw.edu.pl> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2008-12-30Merge branch 'timers-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: hrtimers: fix warning in kernel/hrtimer.c x86: make sure we really have an hpet mapping before using it x86: enable HPET on Fujitsu u9200 linux/timex.h: cleanup for userspace posix-timers: simplify de_thread()->exit_itimers() path posix-timers: check ->it_signal instead of ->it_pid to validate the timer posix-timers: use "struct pid*" instead of "struct task_struct*" nohz: suppress needless timer reprogramming clocksource, acpi_pm.c: put acpi_pm_read_slow() under CONFIG_PCI nohz: no softirq pending warnings for offline cpus hrtimer: removing all ur callback modes, fix hrtimer: removing all ur callback modes, fix hotplug hrtimer: removing all ur callback modes x86: correct link to HPET timer specification rtc-cmos: export second NVRAM bank Fixed up conflicts in sound/drivers/pcsp/pcsp.c and sound/core/hrtimer.c manually.
2008-12-08ALSA: hrtimer - Use hard-irq callbackTakashi Iwai
Use the hard-irq mode for the callback (for possible removal of soft-irq mode in future). Signed-off-by: Takashi Iwai <tiwai@suse.de>
2008-12-08ALSA: timer - Add comments and use ns_to_ktime()Takashi Iwai
Add the license and misc comments at the beginning of the code. Also, use ns_to_ktime() for simplification. Signed-off-by: Takashi Iwai <tiwai@suse.de>
2008-10-24ALSA: Add hrtimer backend for ALSA timer interfaceTakashi Iwai
Added the hrtimer backend for ALSA timer interface. It can be used for the sequencer timer source. Signed-off-by: Takashi Iwai <tiwai@suse.de>