linux/Documentation/locking, branch v4.15

locking/lockdep: Remove the cross-release locking checks

2017-12-12T11:38:51Z

This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y), while it found a number of old bugs initially, was also causing too many false positives that caused people to disable lockdep - which is arguably a worse overall outcome. If we disable cross-release by default but keep the code upstream then in practice the most likely outcome is that we'll allow the situation to degrade gradually, by allowing entropy to introduce more and more false positives, until it overwhelms maintenance capacity. Another bad side effect was that people were trying to work around the false positives by uglifying/complicating unrelated code. There's a marked difference between annotating locking operations and uglifying good code just due to bad lock debugging code ... This gradual decrease in quality happened to a number of debugging facilities in the kernel, and lockdep is pretty complex already, so we cannot risk this outcome. Either cross-release checking can be done right with no false positives, or it should not be included in the upstream kernel. ( Note that it might make sense to maintain it out of tree and go through the false positives every now and then and see whether new bugs were introduced. ) Cc: Byungchul Park Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

Documentation: fix locking rt-mutex doc refs

2017-10-19T18:56:44Z

Signed-off-by: Tom Saeger Signed-off-by: Jonathan Corbet

Merge branch 'linus' into locking/core, to fix up conflicts

2017-09-04T09:01:18Z

Conflicts: mm/page_alloc.c Signed-off-by: Ingo Molnar

rtmutex: update rt-mutex

2017-08-24T19:38:14Z

The rtmutex remove a pending owner bit in in rt_mutex::owner, in commit 8161239a8bcc ("rtmutex: Simplify PI algorithm and make highest prio task get lock") But the document was changed accordingly. Updating it to a meaningful state. BTW, as 'Steven Rostedt' mentioned: There is still technically a "Pending Owner", it's just not called that anymore. The pending owner happens to be the top_waiter of a lock that has no owner and has been woken up to grab the lock. Signed-off-by: Alex Shi Cc: Steven Rostedt Cc: Sebastian Siewior Cc: Mathieu Poirier Cc: Juri Lelli Cc: Thomas Gleixner To: linux-doc@vger.kernel.org To: linux-kernel@vger.kernel.org To: Jonathan Corbet To: Ingo Molnar To: Peter Zijlstra Signed-off-by: Jonathan Corbet

rtmutex: update rt-mutex-design

2017-08-24T19:37:55Z

The rt-mutex-design documents didn't gotten meaningful update from its first version. Even after owner's pending bit was removed in commit 8161239a8bcc ("rtmutex: Simplify PI algorithm and make highest prio task get lock") and priority list 'plist' changed to rbtree. And Peter Zijlstra did some clean up and fix for deadline task changes on tip tree. So update it to latest code and make it meaningful. Steven Rostedt and Sebastian Siewior gave much of comments and input in this doc. Thanks! Signed-off-by: Alex Shi Cc: Steven Rostedt Cc: Sebastian Siewior Cc: Mathieu Poirier Cc: Juri Lelli Cc: Thomas Gleixner To: linux-doc@vger.kernel.org To: linux-kernel@vger.kernel.org To: Jonathan Corbet To: Ingo Molnar To: Peter Zijlstra Signed-off-by: Jonathan Corbet

locking/lockdep: Add 'crossrelease' feature documentation

2017-08-10T10:32:37Z

This document describes the concept of crossrelease feature. Signed-off-by: Byungchul Park Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502089981-21272-15-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar

locking/ww_mutex/Documentation: Update the design document

2017-01-14T10:14:55Z

Document the invariants we maintain for the wait list of ww_mutexes. Signed-off-by: Nicolai Hähnle Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Chris Wilson Cc: Daniel Vetter Cc: Linus Torvalds Cc: Maarten Lankhorst Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dri-devel@lists.freedesktop.org Link: http://lkml.kernel.org/r/1482346000-9927-13-git-send-email-nhaehnle@gmail.com Signed-off-by: Ingo Molnar

locking/lglock: Remove lglock implementation

2016-09-22T13:25:56Z

It is now unused, remove it before someone else thinks its a good idea to use this. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

locking/Documentation/lockdep: Fix spelling mistakes

2016-04-28T08:40:57Z

Signed-off-by: Eric Engestrom Signed-off-by: Peter Zijlstra (Intel) Cc: Jonathan Corbet Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1461566229-4717-2-git-send-email-eric@engestrom.ch Signed-off-by: Ingo Molnar

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

2015-11-04T00:10:43Z

Pull locking changes from Ingo Molnar: "The main changes in this cycle were: - More gradual enhancements to atomic ops: new atomic*_read_ctrl() ops, synchronize atomic_{read,set}() ordering requirements between architectures, add atomic_long_t bitops. (Peter Zijlstra) - Add _{relaxed|acquire|release}() variants for inc/dec atomics and use them in various locking primitives: mutex, rtmutex, mcs, rwsem. This enables weakly ordered architectures (such as arm64) to make use of more locking related optimizations. (Davidlohr Bueso) - Implement atomic[64]_{inc,dec}_relaxed() on ARM. (Will Deacon) - Futex kernel data cache footprint micro-optimization. (Rasmus Villemoes) - pvqspinlock runtime overhead micro-optimization. (Waiman Long) - misc smaller fixlets" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: ARM, locking/atomics: Implement _relaxed variants of atomic[64]_{inc,dec} locking/rwsem: Use acquire/release semantics locking/mcs: Use acquire/release semantics locking/rtmutex: Use acquire/release semantics locking/mutex: Use acquire/release semantics locking/asm-generic: Add _{relaxed|acquire|release}() variants for inc/dec atomics atomic: Implement atomic_read_ctrl() atomic, arch: Audit atomic_{read,set}() atomic: Add atomic_long_t bitops futex: Force hot variables into a single cache line locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VAL locking/osq: Relax atomic semantics locking/qrwlock: Rename ->lock to ->wait_lock locking/Documentation/lockstat: Fix typo - lokcing -> locking locking/atomics, cmpxchg: Privatize the inclusion of asm/cmpxchg.h