linux-toradex.git/kernel/rtmutex.c, branch v2.6.25-rc2

hrtimer: more hrtimer_init_sleeper() fallout.

2008-02-13T14:45:36+00:00

Missed an instance...

  futex_lock_pi()
    hrtimer_init_sleeper()
    rt_mutex_timed_lock()
      rt_mutex_timed_fastlock()
        rt_mutex_slowlock()
          hrtimer_start()

Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar

Use helpers to obtain task pid in printks

2007-10-19T18:53:43+00:00

The task_struct->pid member is going to be deprecated, so start
using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in
the kernel.

The first thing to start with is the pid, printed to dmesg - in
this case we may safely use task_pid_nr(). Besides, printks produce
more (much more) than a half of all the explicit pid usage.

[akpm@linux-foundation.org: git-drm went and changed lots of stuff]
Signed-off-by: Pavel Emelyanov 
Cc: Dave Airlie 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

FUTEX: Tidy up the code

2007-07-16T16:05:49+00:00

The recent PRIVATE and REQUEUE_PI changes to the futex code made it hard to
read.  Tidy it up.

Signed-off-by: Thomas Gleixner 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "futex_requeue_pi optimization"

2007-06-18T16:48:41+00:00

This reverts commit d0aa7a70bf03b9de9e995ab272293be1f7937822.

It not only introduced user space visible changes to the futex syscall,
it is also non-functional and there is no way to fix it proper before
the 2.6.22 release.

The breakage report ( http://lkml.org/lkml/2007/5/12/17 ) went
unanswered, and unfortunately it turned out that the concept is not
feasible at all.  It violates the rtmutex semantics badly by introducing
a virtual owner, which hacks around the coupling of the user-space
pi_futex and the kernel internal rt_mutex representation.

At the moment the only safe option is to remove it fully as it contains
user-space visible changes to broken kernel code, which we do not want
to expose in the 2.6.22 release.

The patch reverts the original patch mostly 1:1, but contains a couple
of trivial manual cleanups which were necessary due to patches, which
touched the same area of code later.

Verified against the glibc tests and my own PI futex tests.

Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Acked-by: Ulrich Drepper 
Cc: Pierre Peiffer 
Signed-off-by: Linus Torvalds

rt-mutex: fix chain walk early wakeup bug

2007-06-09T00:23:34+00:00

Alexey Kuznetsov found some problems in the pi-futex code.

One of the root causes is:

When a wakeup happens, we do not to stop the chain walk so we follow a not
longer relevant locking chain.

Drop out when this happens.

Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Cc: Steven Rostedt 
Cc: Alexey Kuznetsov 
Cc: Ulrich Drepper 
Cc: Eric Dumazet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rt-mutex: fix stale return value

2007-06-09T00:23:34+00:00

Alexey Kuznetsov found some problems in the pi-futex code.

The major problem is a stale return value in rt_mutex_slowlock():

When the pi chain walk returns -EDEADLK, but the waiter was woken up during
the phases where the locks were dropped, the rtmutex could be acquired, but
due to the stale return value -EDEADLK returned to the caller.

Reset the return value in the retry path.

Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Cc: Steven Rostedt 
Cc: Alexey Kuznetsov 
Cc: Ulrich Drepper 
Cc: Eric Dumazet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

futex_requeue_pi optimization

2007-05-09T19:30:55+00:00

This patch provides the futex_requeue_pi functionality, which allows some
threads waiting on a normal futex to be requeued on the wait-queue of a
PI-futex.

This provides an optimization, already used for (normal) futexes, to be used
with the PI-futexes.

This optimization is currently used by the glibc in pthread_broadcast, when
using "normal" mutexes.  With futex_requeue_pi, it can be used with
PRIO_INHERIT mutexes too.

Signed-off-by: Pierre Peiffer 
Cc: Ingo Molnar 
Cc: Ulrich Drepper 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hrtimers: namespace and enum cleanup

2007-02-16T16:13:58+00:00

- hrtimers did not use the hrtimer_restart enum and relied on the implict
  int representation. Fix the prototypes and the functions using the enums.
- Use seperate name spaces for the enumerations
- Convert hrtimer_restart macro to inline function
- Add comments

No functional changes.

[akpm@osdl.org: fix input driver]
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Cc: john stultz 
Cc: Roman Zippel 
Cc: Dmitry Torokhov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] clean up and remove some extra spinlocks from rtmutex

2006-09-29T16:18:09+00:00

Oleg brought up some interesting points about grabbing the pi_lock for some
protections.  In this discussion, I realized that there are some places
that the pi_lock is being grabbed when it really wasn't necessary.  Also
this patch does a little bit of clean up.

This patch basically does three things:

1) renames the "boost" variable to "chain_walk".  Since it is used in
   the debugging case when it isn't going to be boosted.  It better
   describes what the test is going to do if it succeeds.

2) moves get_task_struct to just before the unlocking of the wait_lock.
   This removes duplicate code, and makes it a little easier to read.  The
   owner wont go away while either the pi_lock or the wait_lock are held.

3) removes the pi_locking and owner blocked checking completely from the
   debugging case.  This is because the grabbing the lock and doing the
   check, then releasing the lock is just so full of races.  It's just as
   good to go ahead and call the pi_chain_walk function, since after
   releasing the lock the owner can then block anyway, and we would have
   missed that.  For the debug case, we really do want to do the chain walk
   to test for deadlocks anyway.

[oleg@tv-sign.ru: more of the same]
Signed-of-by: Steven Rostedt 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Oleg Nesterov 
Cc: Esben Nielsen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] reference rt-mutex-design in rtmutex.c

2006-07-31T20:28:43+00:00

In order to prevent Doc Rot, this patch adds a reference to the design
document for rtmutex.c in rtmutex.c.  So when someone needs to update or
change the design of that file they will know that a document actually
exists that explains the design (helping them change it), and hopefully
that they will update the document if they too change the design.

Signed-off-by: Steven Rostedt 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds