linux/kernel/locking/rwsem.c, branch v5.15

locking/rwsem: Add missing __init_rwsem() for PREEMPT_RT

2021-09-02T20:07:17Z

730633f0b7f95 became the first direct caller of __init_rwsem() vs the usual init_rwsem(), exposing PREEMPT_RT's lack thereof. Add it. [ tglx: Move it out of line ] Signed-off-by: Mike Galbraith Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/50a936b7d8f12277d6ec7ed2ef0421a381056909.camel@gmx.de

locking/rtmutex: Extend the rtmutex core to support ww_mutex

2021-08-17T17:05:23Z

Add a ww acquire context pointer to the waiter and various functions and add the ww_mutex related invocations to the proper spots in the locking code, similar to the mutex based variant. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211304.966139174@linutronix.de

locking/rtmutex: Guard regular sleeping locks specific functions

2021-08-17T15:23:27Z

Guard the regular sleeping lock specific functionality, which is used for rtmutex on non-RT enabled kernels and for mutex, rtmutex and semaphores on RT enabled kernels so the code can be reused for the RT specific implementation of spinlocks and rwlocks in a different compilation unit. No functional change. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211303.311535693@linutronix.de

locking/rwsem: Add rtmutex based R/W semaphore implementation

2021-08-17T15:12:47Z

The RT specific R/W semaphore implementation used to restrict the number of readers to one, because a writer cannot block on multiple readers and inherit its priority or budget. The single reader restricting was painful in various ways: - Performance bottleneck for multi-threaded applications in the page fault path (mmap sem) - Progress blocker for drivers which are carefully crafted to avoid the potential reader/writer deadlock in mainline. The analysis of the writer code paths shows that properly written RT tasks should not take them. Syscalls like mmap(), file access which take mmap sem write locked have unbound latencies, which are completely unrelated to mmap sem. Other R/W sem users like graphics drivers are not suitable for RT tasks either. So there is little risk to hurt RT tasks when the RT rwsem implementation is done in the following way: - Allow concurrent readers - Make writers block until the last reader left the critical section. This blocking is not subject to priority/budget inheritance. - Readers blocked on a writer inherit their priority/budget in the normal way. There is a drawback with this scheme: R/W semaphores become writer unfair though the applications which have triggered writer starvation (mostly on mmap_sem) in the past are not really the typical workloads running on a RT system. So while it's unlikely to hit writer starvation, it's possible. If there are unexpected workloads on RT systems triggering it, the problem has to be revisited. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211303.016885947@linutronix.de

Merge tag 'v5.14-rc6' into locking/core, to pick up fixes

2021-08-17T14:16:29Z

Signed-off-by: Ingo Molnar

locking/rwsem: Remove an unused parameter of rwsem_wake()

2021-07-16T16:46:44Z

The 2nd parameter 'count' is not used in this function. The places where the function is called are also modified. Signed-off-by: xuyehan Signed-off-by: Peter Zijlstra (Intel) Acked-by: Waiman Long Link: https://lore.kernel.org/r/1625547043-28103-1-git-send-email-yehanxu1@gmail.com

sched: Change task_struct::state

2021-06-18T09:43:09Z

Change the type and name of task_struct::state. Drop the volatile and shrink it to an 'unsigned int'. Rename it in order to find all uses such that we can use READ_ONCE/WRITE_ONCE as appropriate. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Daniel Bristot de Oliveira Acked-by: Will Deacon Acked-by: Daniel Thompson Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org

locking: Fix typos in comments

2021-03-22T01:45:52Z

Fix ~16 single-word typos in locking code comments. Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Paul E. McKenney Cc: Will Deacon Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

locking/rwsem: Fix comment typo

2021-03-17T08:34:39Z

s/folowing/following/ Signed-off-by: Bhaskar Chowdhury Signed-off-by: Ingo Molnar Acked-by: Randy Dunlap Link: https://lore.kernel.org/r/20210317041806.4096156-1-unixbhaskar@gmail.com

kernel: delete repeated words in comments

2021-02-26T17:41:03Z

Drop repeated words in kernel/events/. {if, the, that, with, time} Drop repeated words in kernel/locking/. {it, no, the} Drop repeated words in kernel/sched/. {in, not} Link: https://lkml.kernel.org/r/20210127023412.26292-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap Acked-by: Will Deacon [kernel/locking/] Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Will Deacon Cc: Mathieu Desnoyers Cc: "Paul E. McKenney" Cc: Juri Lelli Cc: Vincent Guittot Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds