linux/kernel/time/sched_clock.c, branch v5.1

timers/sched_clock: Prevent generic sched_clock wrap caused by tick_freeze()

2019-04-18T12:34:53Z

tick_freeze() introduced by suspend-to-idle in commit 124cf9117c5f ("PM / sleep: Make it possible to quiesce timers during suspend-to-idle") uses timekeeping_suspend() instead of syscore_suspend() during suspend-to-idle. As a consequence generic sched_clock will keep going because sched_clock_suspend() and sched_clock_resume() are not invoked during suspend-to-idle which can result in a generic sched_clock wrap. On a ARM system with suspend-to-idle enabled, sched_clock is registered as "56 bits at 13MHz, resolution 76ns, wraps every 4398046511101ns", which means the real wrapping duration is 8796093022202ns. [ 134.551779] suspend-to-idle suspend (timekeeping_suspend()) [ 1204.912239] suspend-to-idle resume (timekeeping_resume()) ...... [ 1206.912239] suspend-to-idle suspend (timekeeping_suspend()) [ 5880.502807] suspend-to-idle resume (timekeeping_resume()) ...... [ 6000.403724] suspend-to-idle suspend (timekeeping_suspend()) [ 8035.753167] suspend-to-idle resume (timekeeping_resume()) ...... [ 8795.786684] (2)[321:charger_thread]...... [ 8795.788387] (2)[321:charger_thread]...... [ 0.057226] (0)[0:swapper/0]...... [ 0.061447] (2)[0:swapper/2]...... sched_clock was not stopped during suspend-to-idle, and sched_clock_poll hrtimer was not expired because timekeeping_suspend() was invoked during suspend-to-idle. It makes sched_clock wrap at kernel time 8796s. To prevent this, invoke sched_clock_suspend() and sched_clock_resume() in tick_freeze() together with timekeeping_suspend() and timekeeping_resume(). Fixes: 124cf9117c5f (PM / sleep: Make it possible to quiesce timers during suspend-to-idle) Signed-off-by: Chang-An Chen Signed-off-by: Thomas Gleixner Cc: Frederic Weisbecker Cc: Matthias Brugger Cc: John Stultz Cc: Kees Cook Cc: Corey Minyard Cc: Cc: Cc: Stanley Chu Cc: Cc: Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com

sched/clock: Remove license boilerplate

2018-11-23T10:51:22Z

The SPDX identifier defines the license of the file already. No need for the boilerplate. Signed-off-by: Thomas Gleixner Acked-by: Kees Cook Acked-by: Ingo Molnar Acked-by: John Stultz Acked-by: Corey Minyard Cc: Peter Zijlstra Cc: Kate Stewart Cc: Philippe Ombredanne Cc: Peter Anvin Cc: Russell King Cc: Richard Cochran Cc: "Paul E. McKenney" Cc: Nicolas Pitre Cc: David Riley Cc: Colin Cross Cc: Mark Brown Link: https://lkml.kernel.org/r/20181031182253.300140921@linutronix.de

time: Add SPDX license identifiers

2018-11-23T10:51:20Z

Update the time(r) core files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Philippe Ombredanne, Kate Stewart and myself. The data has been created with two independent license scanners and manual inspection. The following files do not contain any direct license information and have been omitted from the big initial SPDX changes: timeconst.bc: The .bc files were not touched time.c, timer.c, timekeeping.c: Licence was deduced from EXPORT_SYMBOL_GPL As those files do not contain direct license references they fall under the project license, i.e. GPL V2 only. Signed-off-by: Thomas Gleixner Acked-by: Kees Cook Acked-by: Ingo Molnar Acked-by: John Stultz Acked-by: Corey Minyard Cc: Peter Zijlstra Cc: Kate Stewart Cc: Philippe Ombredanne Cc: Russell King Cc: Richard Cochran Cc: Nicolas Pitre Cc: David Riley Cc: Colin Cross Cc: Mark Brown Cc: H. Peter Anvin Cc: Paul E. McKenney Link: https://lkml.kernel.org/r/20181031182252.879109557@linutronix.de

time: Remove useless filenames in top level comments

2018-11-23T10:51:20Z

Remove the pointless filenames in the top level comments. They have no value at all and just occupy space. While at it tidy up some of the comments and remove a stale one. Signed-off-by: Thomas Gleixner Acked-by: Nicolas Pitre Acked-by: Kees Cook Acked-by: Ingo Molnar Acked-by: John Stultz Acked-by: Corey Minyard Cc: Peter Zijlstra Cc: Kate Stewart Cc: Philippe Ombredanne Cc: Peter Anvin Cc: Russell King Cc: Richard Cochran Cc: "Paul E. McKenney" Cc: David Riley Cc: Colin Cross Cc: Mark Brown Link: https://lkml.kernel.org/r/20181031182252.794898238@linutronix.de

sched/clock: Move sched clock initialization and merge with generic clock

2018-07-19T22:02:43Z

sched_clock_postinit() initializes a generic clock on systems where no other clock is provided. This function may be called only after timekeeping_init(). Rename sched_clock_postinit to generic_clock_inti() and call it from sched_clock_init(). Move the call for sched_clock_init() until after time_init(). Suggested-by: Peter Zijlstra Signed-off-by: Pavel Tatashin Signed-off-by: Thomas Gleixner Cc: steven.sistare@oracle.com Cc: daniel.m.jordan@oracle.com Cc: linux@armlinux.org.uk Cc: schwidefsky@de.ibm.com Cc: heiko.carstens@de.ibm.com Cc: john.stultz@linaro.org Cc: sboyd@codeaurora.org Cc: hpa@zytor.com Cc: douly.fnst@cn.fujitsu.com Cc: prarit@redhat.com Cc: feng.tang@intel.com Cc: pmladek@suse.com Cc: gnomes@lxorguk.ukuu.org.uk Cc: linux-s390@vger.kernel.org Cc: boris.ostrovsky@oracle.com Cc: jgross@suse.com Cc: pbonzini@redhat.com Link: https://lkml.kernel.org/r/20180719205545.16512-23-pasha.tatashin@oracle.com

timers, sched_clock: Update timeout for clock wrap

2017-03-23T19:30:27Z

The scheduler clock framework may not use the correct timeout for the clock wrap. This happens when a new clock driver calls sched_clock_register() after the kernel called sched_clock_postinit(). In this case the clock wrap timeout is too long thus sched_clock_poll() is called too late and the clock already wrapped. On my ARM system the scheduler was no longer scheduling any other task than the idle task because the sched_clock() wrapped. Signed-off-by: David Engraf Signed-off-by: John Stultz

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27Z

We are going to split out of , which will have to be picked up from other headers and .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

timers, sched/clock: Clean up the code a bit

2015-03-27T07:34:01Z

Trivial cleanups, to improve the readability of the generic sched_clock() code: - Improve and standardize comments - Standardize the coding style - Use vertical spacing where appropriate - etc. No code changed: md5: 19a053b31e0c54feaeff1492012b019a sched_clock.o.before.asm 19a053b31e0c54feaeff1492012b019a sched_clock.o.after.asm Cc: Catalin Marinas Cc: Daniel Thompson Cc: John Stultz Cc: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Russell King Cc: Stephen Boyd Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Ingo Molnar

timers, sched/clock: Avoid deadlock during read from NMI

2015-03-27T07:34:00Z

Currently it is possible for an NMI (or FIQ on ARM) to come in and read sched_clock() whilst update_sched_clock() has locked the seqcount for writing. This results in the NMI handler locking up when it calls raw_read_seqcount_begin(). This patch fixes the NMI safety issues by providing banked clock data. This is a similar approach to the one used in Thomas Gleixner's 4396e058c52e("timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC"). Suggested-by: Stephen Boyd Signed-off-by: Daniel Thompson Signed-off-by: John Stultz Reviewed-by: Stephen Boyd Acked-by: Peter Zijlstra (Intel) Cc: Catalin Marinas Cc: Peter Zijlstra Cc: Russell King Cc: Thomas Gleixner Cc: Will Deacon Link: http://lkml.kernel.org/r/1427397806-20889-6-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar

timers, sched/clock: Remove redundant notrace from update function

2015-03-27T07:33:59Z

Currently update_sched_clock() is marked as notrace but this function is not called by ftrace. This is trivially fixed by removing the mark up. Signed-off-by: Daniel Thompson Signed-off-by: John Stultz Reviewed-by: Stephen Boyd Acked-by: Peter Zijlstra (Intel) Cc: Catalin Marinas Cc: Peter Zijlstra Cc: Russell King Cc: Thomas Gleixner Cc: Will Deacon Link: http://lkml.kernel.org/r/1427397806-20889-5-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar