user/sven/linux.git/kernel/rtmutex.c, branch v3.2

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

2011-10-31T13:20:12Z

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

rcu: Permit rt_mutex_unlock() with irqs disabled

2011-09-29T04:38:43Z

Create a separate lockdep class for the rt_mutex used for RCU priority boosting and enable use of rt_mutex_lock() with irqs disabled. This prevents RCU priority boosting from falling prey to deadlocks when someone begins an RCU read-side critical section in preemptible state, but releases it with an irq-disabled lock held. Unfortunately, the scheduler's runqueue and priority-inheritance locks still must either completely enclose or be completely enclosed by any overlapping RCU read-side critical section. This version removes a redundant local_irq_restore() noted by Yong Zhang. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney

plist: Remove the need to supply locks to plist heads

2011-07-08T12:02:53Z

This was legacy code brought over from the RT tree and is no longer necessary. Signed-off-by: Dima Zavin Acked-by: Thomas Gleixner Cc: Daniel Walker Cc: Steven Rostedt Cc: Peter Zijlstra Cc: Andi Kleen Cc: Lai Jiangshan Link: http://lkml.kernel.org/r/1310084879-10351-2-git-send-email-dima@android.com Signed-off-by: Ingo Molnar

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

2011-01-28T02:13:51Z

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

rtmutes: Convert rtmutex.lock to raw_spinlock

2009-12-14T22:55:33Z

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

sched: Convert pi_lock to raw_spinlock

2009-12-14T22:55:33Z

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

rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock()

2009-08-06T03:50:21Z

In the event of a lock steal or owner died, rt_mutex_start_proxy_lock() will give the rt_mutex to the waiting task, but it fails to release the wait_lock. This leads to subsequent deadlocks when other tasks try to acquire the rt_mutex. I also removed a few extra blank lines that really spaced this routine out. I must have been high on the \n when I wrote this originally... Signed-off-by: Darren Hart Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Dinakar Guniguntala Cc: John Stultz LKML-Reference: <4A79D7F1.4000405@us.ibm.com> Signed-off-by: Ingo Molnar

trivial: fix ETIMEOUT -> ETIMEDOUT typos

2009-06-12T16:01:50Z

fix ETIMEOUT -> ETIMEDOUT typos Signed-off-by: Jean Delvare Signed-off-by: Jiri Kosina

Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-06-10T23:19:40Z

* 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: spinlock: Add missing __raw_spin_lock_flags() stub for UP mutex: add atomic_dec_and_mutex_lock(), fix locking, rtmutex.c: Documentation cleanup mutex: add atomic_dec_and_mutex_lock()

locking, rtmutex.c: Documentation cleanup

2009-04-29T21:20:17Z

Two minor updates on functions documentation: - Updated documentation for function rt_mutex_unlock(), which contained an incorrect name - Removed extra '*' from comment in function rt_mutex_destroy() [ Impact: cleanup ] Signed-off-by: Luis Henriques Cc: Steven Rostedt LKML-Reference: <20090429205451.GA23154@hades.domain.com> Signed-off-by: Ingo Molnar