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  1. 02 2月, 2011 1 次提交
  3. 21 10月, 2010 1 次提交
  5. 23 7月, 2010 1 次提交
  7. 28 5月, 2010 1 次提交
  9. 05 2月, 2010 1 次提交
  11. 22 8月, 2009 1 次提交
    • J
      time: Introduce CLOCK_REALTIME_COARSE · da15cfda
      由 john stultz 提交于 
      After talking with some application writers who want very fast, but not
fine-grained timestamps, I decided to try to implement new clock_ids
to clock_gettime(): CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE
which returns the time at the last tick. This is very fast as we don't
have to access any hardware (which can be very painful if you're using
something like the acpi_pm clocksource), and we can even use the vdso
clock_gettime() method to avoid the syscall. The only trade off is you
only get low-res tick grained time resolution.

This isn't a new idea, I know Ingo has a patch in the -rt tree that made
the vsyscall gettimeofday() return coarse grained time when the
vsyscall64 sysctrl was set to 2. However this affects all applications
on a system.

With this method, applications can choose the proper speed/granularity
trade-off for themselves.
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: nikolag@ca.ibm.com
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: arjan@infradead.org
Cc: jonathan@jonmasters.org
LKML-Reference: <1250734414.6897.5.camel@localhost.localdomain>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      da15cfda
  13. 04 8月, 2009 1 次提交
  15. 14 1月, 2009 1 次提交
  17. 21 12月, 2008 1 次提交
  19. 13 12月, 2008 2 次提交
    • O
      posix-timers: check ->it_signal instead of ->it_pid to validate the timer · 89992102
      由 Oleg Nesterov 提交于 
      Impact: clean up, speed up

->it_pid (was ->it_process) has also a special meaning: if it is NULL,
the timer is under deletion or it wasn't initialized yet. We can check
->it_signal != NULL instead, this way we can

	- simplify sys_timer_create() a bit

	- remove yet another check from lock_timer()

	- move put_pid(->it_pid) into release_posix_timer() which
	  runs outside of ->it_lock
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      89992102
    • O
      posix-timers: use "struct pid*" instead of "struct task_struct*" · 27af4245
      由 Oleg Nesterov 提交于 
      Impact: restructure, clean up code

k_itimer holds the ref to the ->it_process until sys_timer_delete(). This
allows to pin up to RLIMIT_SIGPENDING dead task_struct's. Change the code
to use "struct pid *" instead.

The patch doesn't kill ->it_process, it places ->it_pid into the union.
->it_process is still used by do_cpu_nanosleep() as before. It would be
trivial to change the nanosleep code as well, but since it uses it_process
in a special way I think it is better to keep this field for grep.

The patch bloats the kernel by 104 bytes and it also adds the new pointer,
->it_signal, to k_itimer. It is used by lock_timer() to verify that the
found timer was not created by another process. It is not clear why do we
use the global database (and thus the global idr_lock) for posix timers.
We still need the signal_struct->posix_timers which contains all useable
timers, perhaps it is better to use some form of per-process array
instead.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      27af4245
  21. 03 10月, 2008 1 次提交
  23. 24 9月, 2008 9 次提交
  25. 06 9月, 2008 1 次提交
  27. 21 8月, 2008 1 次提交
    • J
      clocksource: introduce CLOCK_MONOTONIC_RAW · 2d42244a
      由 John Stultz 提交于 
      In talking with Josip Loncaric, and his work on clock synchronization (see
btime.sf.net), he mentioned that for really close synchronization, it is
useful to have access to "hardware time", that is a notion of time that is
not in any way adjusted by the clock slewing done to keep close time sync.

Part of the issue is if we are using the kernel's ntp adjusted
representation of time in order to measure how we should correct time, we
can run into what Paul McKenney aptly described as "Painting a road using
the lines we're painting as the guide".

I had been thinking of a similar problem, and was trying to come up with a
way to give users access to a purely hardware based time representation
that avoided users having to know the underlying frequency and mask values
needed to deal with the wide variety of possible underlying hardware
counters.

My solution is to introduce CLOCK_MONOTONIC_RAW.  This exposes a
nanosecond based time value, that increments starting at bootup and has no
frequency adjustments made to it what so ever.

The time is accessed from userspace via the posix_clock_gettime() syscall,
passing CLOCK_MONOTONIC_RAW as the clock_id.
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: NRoman Zippel <zippel@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      2d42244a
  29. 26 7月, 2008 2 次提交
  31. 24 7月, 2008 2 次提交
    • O
      posix-timers: fix posix_timer_event() vs dequeue_signal() race · ba661292
      由 Oleg Nesterov 提交于 
      The bug was reported and analysed by Mark McLoughlin <markmc@redhat.com>,
the patch is based on his and Roland's suggestions.

posix_timer_event() always rewrites the pre-allocated siginfo before sending
the signal. Most of the written info is the same all the time, but memset(0)
is very wrong. If ->sigq is queued we can race with collect_signal() which
can fail to find this siginfo looking at .si_signo, or copy_siginfo() can
copy the wrong .si_code/si_tid/etc.

In short, sys_timer_settime() can in fact stop the active timer, or the user
can receive the siginfo with the wrong .si_xxx values.

Move "memset(->info, 0)" from posix_timer_event() to alloc_posix_timer(),
change send_sigqueue() to set .si_overrun = 0 when ->sigq is not queued.
It would be nice to move the whole sigq->info initialization from send to
create path, but this is not easy to do without uglifying timer_create()
further.

As Roland rightly pointed out, we need more cleanups/fixes here, see the
"FIXME" comment in the patch. Hopefully this patch makes sense anyway, and
it can mask the most bad implications.
Reported-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: Oliver Pinter <oliver.pntr@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

 kernel/posix-timers.c |   17 +++++++++++++----
 kernel/signal.c       |    1 +
 2 files changed, 14 insertions(+), 4 deletions(-)
      ba661292
    • O
      posix-timers: do_schedule_next_timer: fix the setting of ->si_overrun · 54da1174
      由 Oleg Nesterov 提交于 
      do_schedule_next_timer() sets info->si_overrun = timr->it_overrun_last,
this discards the already accumulated overruns.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: Oliver Pinter <oliver.pntr@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      54da1174
  33. 30 4月, 2008 1 次提交
  35. 19 4月, 2008 1 次提交
  37. 15 2月, 2008 1 次提交
  39. 10 2月, 2008 1 次提交
    • O
      hrtimer: fix *rmtp handling in hrtimer_nanosleep() · 080344b9
      由 Oleg Nesterov 提交于 
      Spotted by Pavel Emelyanov and Alexey Dobriyan.

hrtimer_nanosleep() sets restart_block->arg1 = rmtp, but this rmtp points to
the local variable which lives in the caller's stack frame. This means that
if sys_restart_syscall() actually happens and it is interrupted as well, we
don't update the user-space variable, but write into the already dead stack
frame.

Introduced by commit 04c22714
hrtimer: Rework hrtimer_nanosleep to make sys_compat_nanosleep easier

Change the callers to pass "__user *rmtp" to hrtimer_nanosleep(), and change
hrtimer_nanosleep() to use copy_to_user() to actually update *rmtp.

Small problem remains. man 2 nanosleep states that *rtmp should be written if
nanosleep() was interrupted (it says nothing whether it is OK to update *rmtp
if nanosleep returns 0), but (with or without this patch) we can dirty *rem
even if nanosleep() returns 0.

NOTE: this patch doesn't change compat_sys_nanosleep(), because it has other
bugs. Fixed by the next patch.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Pavel Emelyanov <xemul@sw.ru>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Toyo Abe <toyoa@mvista.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

 include/linux/hrtimer.h |    2 -
 kernel/hrtimer.c        |   51 +++++++++++++++++++++++++-----------------------
 kernel/posix-timers.c   |   14 +------------
 3 files changed, 30 insertions(+), 37 deletions(-)
      080344b9
  41. 09 2月, 2008 1 次提交
  43. 06 2月, 2008 1 次提交
    • D
      timerfd: new timerfd API · 4d672e7a
      由 Davide Libenzi 提交于 
      This is the new timerfd API as it is implemented by the following patch:

int timerfd_create(int clockid, int flags);
int timerfd_settime(int ufd, int flags,
		    const struct itimerspec *utmr,
		    struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);

The timerfd_create() API creates an un-programmed timerfd fd.  The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.

The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not
NULL).

The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter.  Otherwise it's a relative time.

The timerfd_gettime() API returns the next expiration time of the timer, or
{0, 0} if the timerfd has not been set yet.

Like the previous timerfd API implementation, read(2) and poll(2) are
supported (with the same interface).  Here's a simple test program I used to
exercise the new timerfd APIs:

http://www.xmailserver.org/timerfd-test2.c

[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: fix ia64 build]
[akpm@linux-foundation.org: fix m68k build]
[akpm@linux-foundation.org: fix mips build]
[akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds]
[heiko.carstens@de.ibm.com: fix s390]
[akpm@linux-foundation.org: fix powerpc build]
[akpm@linux-foundation.org: fix sparc64 more]
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4d672e7a
  45. 03 2月, 2008 1 次提交
  47. 20 10月, 2007 1 次提交
  49. 19 10月, 2007 1 次提交
  51. 17 10月, 2007 1 次提交
  53. 15 10月, 2007 1 次提交
  55. 23 8月, 2007 2 次提交
    • O
      posix-timers: fix creation race · d02479bd
      由 Oleg Nesterov 提交于 
      sys_timer_create() sets ->it_process and unlocks ->siglock, then checks
tmr->it_sigev_notify to define if get_task_struct() is needed.

We already passed ->it_id to the caller, another thread can delete this timer
and free its memory in between.

As a minimal fix, move this code under ->siglock, sys_timer_delete() takes it
too before calling release_posix_timer().  A proper serialization would be to
take ->it_lock, we add a partly initialized timer on posix_timers_id, not
good.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d02479bd
    • T
      posix-timers: fix deletion race · 179394af
      由 Thomas Gleixner 提交于 
      timer_delete does:
	lock_timer();
	timer->it_process = NULL;
	unlock_timer();
	release_posix_timer();

timer->it_process is checked in lock_timer() to prevent access to a
timer, which is on the way to be deleted, but the check happens after
idr_lock is dropped. This allows release_posix_timer() to delete the
timer before the lock code can check the timer:

  CPU 0				CPU 1

  lock_timer();
  timer->it_process = NULL;
  unlock_timer();
				lock_timer()
					spin_lock(idr_lock);
					timer = idr_find();
					spin_lock(timer->lock);
					spin_unlock(idr_lock);
  release_posix_timer();
	spin_lock(idr_lock);
	idr_remove(timer);
	spin_unlock(idr_lock);
	free_timer(timer);
					if (timer->......)

Change the locking to prevent this.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      179394af