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  1. 24 Sep, 2008 4 commits
  3. 25 Jul, 2008 2 commits
  5. 23 Jul, 2008 2 commits
    • Oleg Nesterov's avatar
      posix-timers: fix posix_timer_event() vs dequeue_signal() race · ba661292
      Oleg Nesterov authored 
      
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: default avatarMark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarOleg 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: default avatarThomas Gleixner <tglx@linutronix.de>

 kernel/posix-timers.c |   17 +++++++++++++----
 kernel/signal.c       |    1 +
 2 files changed, 14 insertions(+), 4 deletions(-)
      ba661292
    • Oleg Nesterov's avatar
      posix-timers: do_schedule_next_timer: fix the setting of ->si_overrun · 54da1174
      Oleg Nesterov authored 
      
do_schedule_next_timer() sets info->si_overrun = timr->it_overrun_last,
this discards the already accumulated overruns.
Signed-off-by: default avatarOleg 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: default avatarThomas Gleixner <tglx@linutronix.de>
      54da1174
  7. 30 Apr, 2008 1 commit
  9. 19 Apr, 2008 1 commit
  11. 14 Feb, 2008 1 commit
  13. 10 Feb, 2008 1 commit
    • Oleg Nesterov's avatar
      hrtimer: fix *rmtp handling in hrtimer_nanosleep() · 080344b9
      Oleg Nesterov authored 
      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: default avatarOleg 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: default avatarThomas 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
  15. 08 Feb, 2008 1 commit
  17. 05 Feb, 2008 1 commit
    • Davide Libenzi's avatar
      timerfd: new timerfd API · 4d672e7a
      Davide Libenzi authored 
      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: default avatarDavide 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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4d672e7a
  19. 03 Feb, 2008 1 commit
  21. 19 Oct, 2007 1 commit
  23. 18 Oct, 2007 1 commit
  25. 17 Oct, 2007 1 commit
  27. 14 Oct, 2007 1 commit
  29. 23 Aug, 2007 2 commits
    • Oleg Nesterov's avatar
      posix-timers: fix creation race · d02479bd
      Oleg Nesterov authored 
      
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: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d02479bd
    • Thomas Gleixner's avatar
      posix-timers: fix deletion race · 179394af
      Thomas Gleixner authored 
      
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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      179394af
  31. 20 Jul, 2007 1 commit
    • Paul Mundt's avatar
      mm: Remove slab destructors from kmem_cache_create(). · 20c2df83
      Paul Mundt authored 
      Slab destructors were no longer supported after Christoph's
c59def9f

 change. They've been
BUGs for both slab and slub, and slob never supported them
either.

This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
      20c2df83
  33. 21 Jun, 2007 1 commit
    • Thomas Gleixner's avatar
      posix-timers: Prevent softirq starvation by small intervals and SIG_IGN · 58229a18
      Thomas Gleixner authored 
      
posix-timers which deliver an ignored signal are currently rearmed in
the timer softirq: This is necessary because the timer needs to be
delivered again when SIG_IGN is removed. This is not a problem, when
the interval is reasonable.

With high resolution timers enabled one might arm a posix timer with a
very small interval and ignore the signal. This might lead to a
softirq starvation when the interval is so small that the timer is
requeued onto the softirq pending list right away.

This problem was pointed out by Jan Kiszka. Thanks Jan !

The correct solution would be to stop the timer, when the signal is
ignored and rearm it when SIG_IGN is removed. Unfortunately this
requires modification in sigaction and involves non trivial sighand
locking. It's too late in the release cycle for such a change.

For now we just keep the timer running and enforce that the timer only
fires every jiffie. This does not break anything as we keep the
overrun counter correct. It adds a little inaccuracy to the
timer_gettime() interface, but...

The more complex change is necessary anyway to fix another short
coming of the current implementation, which I discovered while looking
at this problem: A pending signal is discarded when SIG_IGN is set. In
case that a posixtimer signal is pending then it is discarded as well,
but when SIG_IGN is removed later nothing rearms the timer. This is
not new, it's that way since posix timers have been merged. So nothing
to worry about right now.

I have a working solution to fix all of this, but the impact is too
large for both stable and 2.6.22. I'm going to send it out for review
in the next days.

This should go into 2.6.21.stable as well.
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Stable Team <stable@kernel.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      58229a18
  35. 08 May, 2007 1 commit
  37. 16 Feb, 2007 2 commits
  39. 11 Feb, 2007 1 commit
  41. 07 Dec, 2006 1 commit
  43. 03 Oct, 2006 1 commit
  45. 29 Sep, 2006 1 commit
  47. 26 Mar, 2006 3 commits
  49. 23 Mar, 2006 1 commit
  51. 17 Mar, 2006 1 commit
  53. 01 Feb, 2006 4 commits
  55. 15 Jan, 2006 1 commit