linux-stable.git/kernel/time/hrtimer.c, branch v4.14.18

hrtimer: Reset hrtimer cpu base proper on CPU hotplug

2018-01-31T13:03:49+00:00

commit d5421ea43d30701e03cadc56a38854c36a8b4433 upstream.

The hrtimer interrupt code contains a hang detection and mitigation
mechanism, which prevents that a long delayed hrtimer interrupt causes a
continous retriggering of interrupts which prevent the system from making
progress. If a hang is detected then the timer hardware is programmed with
a certain delay into the future and a flag is set in the hrtimer cpu base
which prevents newly enqueued timers from reprogramming the timer hardware
prior to the chosen delay. The subsequent hrtimer interrupt after the delay
clears the flag and resumes normal operation.

If such a hang happens in the last hrtimer interrupt before a CPU is
unplugged then the hang_detected flag is set and stays that way when the
CPU is plugged in again. At that point the timer hardware is not armed and
it cannot be armed because the hang_detected flag is still active, so
nothing clears that flag. As a consequence the CPU does not receive hrtimer
interrupts and no timers expire on that CPU which results in RCU stalls and
other malfunctions.

Clear the flag along with some other less critical members of the hrtimer
cpu base to ensure starting from a clean state when a CPU is plugged in.

Thanks to Paul, Sebastian and Anna-Maria for their help to get down to the
root cause of that hard to reproduce heisenbug. Once understood it's
trivial and certainly justifies a brown paperbag.

Fixes: 41d2e4949377 ("hrtimer: Tune hrtimer_interrupt hang logic")
Reported-by: Paul E. McKenney 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Sebastian Sewior 
Cc: Anna-Maria Gleixner 
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801261447590.2067@nanos
Signed-off-by: Greg Kroah-Hartman

nanosleep: Use get_timespec64() and put_timespec64()

2017-06-30T08:14:14+00:00

Usage of these apis and their compat versions makes
the syscalls: clock_nanosleep and nanosleep and
their compat implementations simpler.

This is a preparatory patch to isolate data conversions to
struct timespec64 at userspace boundaries. This helps contain
the changes needed to transition to new y2038 safe types.

Signed-off-by: Deepa Dinamani 
Signed-off-by: Al Viro

posix-timers: Make nanosleep timespec argument const

2017-06-13T22:00:47+00:00

No nanosleep implementation modifies the rqtp argument. Mark is const.

Signed-off-by: Thomas Gleixner 
Cc: Al Viro 
Cc: John Stultz 
Cc: Peter Zijlstra

posix-timers: Kill ->nsleep_restart()

2017-06-13T22:00:42+00:00

No more users.

Signed-off-by: Al Viro 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170607084241.28657-8-viro@ZenIV.linux.org.uk

hrtimers/posix-timers: Merge nanosleep timespec copyout logics into a new helper

2017-06-13T22:00:42+00:00

Signed-off-by: Al Viro 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170607084241.28657-7-viro@ZenIV.linux.org.uk

time/posix-timers: Move the compat copyouts to the nanosleep implementations

2017-06-13T22:00:42+00:00

Turn restart_block.nanosleep.{rmtp,compat_rmtp} into a tagged union (kind =
1 -> native, kind = 2 -> compat, kind = 0 -> nothing) and make the places
doing actual copyout handle compat as well as native (that will become a
helper in the next commit).  Result: compat wrappers, messing with
reassignments, etc. are gone.

[ tglx: Folded in a variant of Peter Zijlstras enum patch ]

Signed-off-by: Al Viro 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170607084241.28657-6-viro@ZenIV.linux.org.uk

hrtimer: Move copyout of remaining time to do_nanosleep()

2017-06-13T22:00:41+00:00

The hrtimer nanosleep() implementation can be simplified by moving the copy
out of the remaining time to do_nanosleep() which is shared between the
real nanosleep function and the restart function.

The pointer to the timespec64 which is updated is already stored in the
restart block at the call site, so the seperate handling of nanosleep and
restart function can be avoided.

[ tglx: Added changelog ]

Signed-off-by: Al Viro 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170607084241.28657-4-viro@ZenIV.linux.org.uk

hrtimer_nanosleep(): Pass rmtp in restart_block

2017-06-13T22:00:40+00:00

Store the pointer to the timespec which gets updated with the remaining
time in the restart block and remove the function argument.

[ tglx: Added changelog ]

Signed-off-by: Al Viro 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170607084241.28657-3-viro@ZenIV.linux.org.uk

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2017-05-03T02:09:35+00:00

Pull trivial tree updates from Jiri Kosina.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
  tty: fix comment for __tty_alloc_driver()
  init/main: properly align the multi-line comment
  init/main: Fix double "the" in comment
  Fix dead URLs to ftp.kernel.org
  drivers: Clean up duplicated email address
  treewide: Fix typo in xml/driver-api/basics.xml
  tools/testing/selftests/powerpc: remove redundant CFLAGS in Makefile: "-Wall -O2 -Wall" -> "-O2 -Wall"
  selftests/timers: Spelling s/privledges/privileges/
  HID: picoLCD: Spelling s/REPORT_WRTIE_MEMORY/REPORT_WRITE_MEMORY/
  net: phy: dp83848: Fix Typo
  UBI: Fix typos
  Documentation: ftrace.txt: Correct nice value of 120 priority
  net: fec: Fix typo in error msg and comment
  treewide: Fix typos in printk

time: Change k_clock nsleep() to use timespec64

2017-04-14T19:49:56+00:00

struct timespec is not y2038 safe on 32 bit machines.  Replace uses of
struct timespec with struct timespec64 in the kernel.

The syscall interfaces themselves will be changed in a separate series.

Note that the restart_block parameter for nanosleep has also been left
unchanged and will be part of syscall series noted above.

Signed-off-by: Deepa Dinamani 
Cc: y2038@lists.linaro.org
Cc: john.stultz@linaro.org
Cc: arnd@arndb.de
Link: http://lkml.kernel.org/r/1490555058-4603-8-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Thomas Gleixner