linux-toradex.git/kernel/rtmutex-debug.c, branch v4.2.4

locking: Move the rtmutex code to kernel/locking/

2013-11-06T08:23:59+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-p9ijt8div0hwldexwfm4nlhj@git.kernel.org
[ Fixed build failure in kernel/rcu/tree_plugin.h. ]
Signed-off-by: Ingo Molnar

sched/rt: Move rt specific bits into new header file

2013-02-07T19:51:08+00:00

Move rt scheduler definitions out of include/linux/sched.h into
new file include/linux/sched/rt.h

Signed-off-by: Clark Williams 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lan
Signed-off-by: Ingo Molnar

lockdep, rtmutex, bug: Show taint flags on error

2011-12-06T07:16:49+00:00

Show the taint flags in all lockdep and rtmutex-debug error messages.

Signed-off-by: Ben Hutchings 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1319773015.6759.30.camel@deadeye
Signed-off-by: Ingo Molnar

kernel: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
onto the isolated export header for faster compile times.

Nothing to see here but a whole lot of instances of:

  -#include 
  +#include 

This commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.

Signed-off-by: Paul Gortmaker

rtmutex: Add missing rcu_read_unlock() in debug_rt_mutex_print_deadlock()

2011-10-05T11:20:24+00:00

Signed-off-by: Thomas Gleixner

rtmutex: Cleanup the debug code

2011-09-12T11:42:32+00:00

Use the existing lock debugging macros.

Signed-off-by: Thomas Gleixner

rtmutex: Simplify PI algorithm and make highest prio task get lock

2011-01-28T02:13:51+00:00

In current rtmutex, the pending owner may be boosted by the tasks
in the rtmutex's waitlist when the pending owner is deboosted
or a task in the waitlist is boosted. This boosting is unrelated,
because the pending owner does not really take the rtmutex.
It is not reasonable.

Example.

time1:
A(high prio) onwers the rtmutex.
B(mid prio) and C (low prio) in the waitlist.

time2
A release the lock, B becomes the pending owner
A(or other high prio task) continues to run. B's prio is lower
than A, so B is just queued at the runqueue.

time3
A or other high prio task sleeps, but we have passed some time
The B and C's prio are changed in the period (time2 ~ time3)
due to boosting or deboosting. Now C has the priority higher
than B. ***Is it reasonable that C has to boost B and help B to
get the rtmutex?

NO!! I think, it is unrelated/unneed boosting before B really
owns the rtmutex. We should give C a chance to beat B and
win the rtmutex.

This is the motivation of this patch. This patch *ensures*
only the top waiter or higher priority task can take the lock.

How?
1) we don't dequeue the top waiter when unlock, if the top waiter
   is changed, the old top waiter will fail and go to sleep again.
2) when requiring lock, it will get the lock when the lock is not taken and:
   there is no waiter OR higher priority than waiters OR it is top waiter.
3) In any time, the top waiter is changed, the top waiter will be woken up.

The algorithm is much simpler than before, no pending owner, no
boosting for pending owner.

Other advantage of this patch:
1) The states of a rtmutex are reduced a half, easier to read the code.
2) the codes become shorter.
3) top waiter is not dequeued until it really take the lock:
   they will retain FIFO when it is stolen.

Not advantage nor disadvantage
1) Even we may wakeup multiple waiters(any time when top waiter changed),
   we hardly cause "thundering herd",
   the number of wokenup task is likely 1 or very little.
2) two APIs are changed.
   rt_mutex_owner() will not return pending owner, it will return NULL when
                    the top waiter is going to take the lock.
   rt_mutex_next_owner() always return the top waiter.
	                 will not return NULL if we have waiters
                         because the top waiter is not dequeued.

   I have fixed the code that use these APIs.

need updated after this patch is accepted
1) Document/*
2) the testcase scripts/rt-tester/t4-l2-pi-deboost.tst

Signed-off-by:  Lai Jiangshan 
LKML-Reference: <4D3012D5.4060709@cn.fujitsu.com>
Reviewed-by: Steven Rostedt 
Signed-off-by: Steven Rostedt

sched: Convert pi_lock to raw_spinlock

2009-12-14T22:55:33+00:00

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra 
Acked-by: Ingo Molnar

Don't operate with pid_t in rtmutex tester

2008-02-08T17:22:41+00:00

The proper behavior to store task's pid and get this task later is to get the
struct pid pointer and get the task with the pid_task() call.

Make it for rt_mutex_waiter->deadlock_task_pid field.

Signed-off-by: Pavel Emelyanov 
Cc: "Eric W. Biederman" 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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