Fix kernel-doc notation in linux/mutex.h and kernel/mutex.c,
then add these 2 files to the kernel-locking docbook as the
Mutex API reference chapter.

Add one API function to mutex-design.txt and correct a typo in
that file.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <20100902154816.6cc2f9ad.randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/mutex.h:136: warning: 'mutex_lock' declared inline after being called
 include/linux/mutex.h:136: warning: previous declaration of 'mutex_lock' was here

uninline it.

[ Impact: clean up and uninline, address compiler warning ]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <200904292318.n3TNIsi6028340@imap1.linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Much like the atomic_dec_and_lock() function in which we take an hold a
spin_lock if we drop the atomic to 0 this function takes and holds the
mutex if we dec the atomic to 0.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.410913479@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Much like the atomic_dec_and_lock() function in which we take an hold a
spin_lock if we drop the atomic to 0 this function takes and holds the
mutex if we dec the atomic to 0.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.410913479@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Change mutex contention behaviour such that it will sometimes busy wait on
acquisition - moving its behaviour closer to that of spinlocks.

This concept got ported to mainline from the -rt tree, where it was originally
implemented for rtmutexes by Steven Rostedt, based on work by Gregory Haskins.

Testing with Ingo's test-mutex application (http://lkml.org/lkml/2006/1/8/50)
gave a 345% boost for VFS scalability on my testbox:

 # ./test-mutex-shm V 16 10 | grep "^avg ops"
 avg ops/sec:               296604

 # ./test-mutex-shm V 16 10 | grep "^avg ops"
 avg ops/sec:               85870

The key criteria for the busy wait is that the lock owner has to be running on
a (different) cpu. The idea is that as long as the owner is running, there is a
fair chance it'll release the lock soon, and thus we'll be better off spinning
instead of blocking/scheduling.

Since regular mutexes (as opposed to rtmutexes) do not atomically track the
owner, we add the owner in a non-atomic fashion and deal with the races in
the slowpath.

Furthermore, to ease the testing of the performance impact of this new code,
there is means to disable this behaviour runtime (without having to reboot
the system), when scheduler debugging is enabled (CONFIG_SCHED_DEBUG=y),
by issuing the following command:

 # echo NO_OWNER_SPIN > /debug/sched_features

This command re-enables spinning again (this is also the default):

 # echo OWNER_SPIN > /debug/sched_features
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: improve documentation

It's nice to say that mutex_trylock follows the spin_trylock convention.
It's a lot nicer if the comment also says which that is...  make it so.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Similar to mutex_lock_interruptible, it can be interrupted by a fatal
signal only.
Signed-off-by: NLiam R. Howlett <howlett@gmail.com>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>

Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The fancy mutex_lock fastpath has too many indirections to track the caller
hence all contentions are perceived to come from mutex_lock().

Avoid this by explicitly not using the fastpath code (it was disabled already
anyway).
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It's not sane to use mutex_lock_interruptible() and to then ignore the result.

Ditto down_interruptible(), but I'm lazy.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix a number of kernel-doc entries for header files in include/linux by
making sure they begin with the appropriate '/**' notation and use @var
notation.
Signed-off-by: NRobert P. J. Day <rpjday@mindspring.com>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

md_open takes ->reconfig_mutex which causes lockdep to complain.  This
(normally) doesn't have deadlock potential as the possible conflict is with a
reconfig_mutex in a different device.

I say "normally" because if a loop were created in the array->member hierarchy
a deadlock could happen.  However that causes bigger problems than a deadlock
and should be fixed independently.

So we flag the lock in md_open as a nested lock.  This requires defining
mutex_lock_interruptible_nested.

Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Name some of the remaning 'old_style_spin_init' locks
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Use the lock validator framework to prove mutex locking correctness.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

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: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Let's switch mutex_debug_check_no_locks_freed() to take (addr, len) as
arguments instead, since all its callers were just calculating the 'to'
address for themselves anyway... (and sometimes doing so badly).
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

mutex implementation, core files: just the basic subsystem, no users of it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@infradead.org>