Commit Graph

14 Commits

Author SHA1 Message Date
Thomas Gleixner 36cf3b5c3b FUTEX: Tidy up the code
The recent PRIVATE and REQUEUE_PI changes to the futex code made it hard to
read.  Tidy it up.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:49 -07:00
Thomas Gleixner bd197234b0 Revert "futex_requeue_pi optimization"
This reverts commit d0aa7a70bf.

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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-18 09:48:41 -07:00
Thomas Gleixner 1a539a8728 rt-mutex: fix chain walk early wakeup bug
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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-08 17:23:34 -07:00
Thomas Gleixner c0d1d2bf5a rt-mutex: fix stale return value
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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-08 17:23:34 -07:00
Pierre Peiffer d0aa7a70bf futex_requeue_pi optimization
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 <pierre.peiffer@bull.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:55 -07:00
Thomas Gleixner c9cb2e3d7c [PATCH] hrtimers: namespace and enum cleanup
- 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 <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-16 08:13:58 -08:00
Steven Rostedt db630637b2 [PATCH] clean up and remove some extra spinlocks from rtmutex
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 <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Esben Nielsen <nielsen.esben@googlemail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:09 -07:00
Steven Rostedt d07fe82c24 [PATCH] reference rt-mutex-design in rtmutex.c
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 <rostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-31 13:28:43 -07:00
Ingo Molnar 36c8b58689 [PATCH] sched: cleanup, remove task_t, convert to struct task_struct
cleanup: remove task_t and convert all the uses to struct task_struct. I
introduced it for the scheduler anno and it was a mistake.

Conversion was mostly scripted, the result was reviewed and all
secondary whitespace and style impact (if any) was fixed up by hand.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:27:11 -07:00
Ingo Molnar 9a11b49a80 [PATCH] lockdep: better lock debugging
Generic lock debugging:

 - generalized lock debugging framework. For example, a bug in one lock
   subsystem turns off debugging in all lock subsystems.

 - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
   the mutex/rtmutex debugging code: it caused way too much prototype
   hackery, and lockdep will give the same information anyway.

 - ability to do silent tests

 - check lock freeing in vfree too.

 - more finegrained debugging options, to allow distributions to
   turn off more expensive debugging features.

There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes.  (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)

Here are the current debugging options:

CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y

which do:

 config DEBUG_MUTEXES
          bool "Mutex debugging, basic checks"

 config DEBUG_LOCK_ALLOC
         bool "Detect incorrect freeing of live mutexes"

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:27:01 -07:00
Thomas Gleixner 95e02ca9bb [PATCH] rtmutex: Propagate priority settings into PI lock chains
When the priority of a task, which is blocked on a lock, changes we must
propagate this change into the PI lock chain.  Therefor the chain walk code
is changed to get rid of the references to current to avoid false positives
in the deadlock detector, as setscheduler might be called by a task which
holds the lock on which the task whose priority is changed is blocked.

Also add some comments about the get/put_task_struct usage to avoid
confusion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:48 -07:00
Ingo Molnar 0cdbee9920 [PATCH] pi-futex: rt mutex futex api
Add proxy-locking rt-mutex functionality needed by pi-futexes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:47 -07:00
Thomas Gleixner 61a8712286 [PATCH] pi-futex: rt mutex tester
RT-mutex tester: scriptable tester for rt mutexes, which allows userspace
scripting of mutex unit-tests (and dynamic tests as well), using the actual
rt-mutex implementation of the kernel.

[akpm@osdl.org: fixlet]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:47 -07:00
Ingo Molnar 23f78d4a03 [PATCH] pi-futex: rt mutex core
Core functions for the rt-mutex subsystem.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:47 -07:00