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* locking/lockdep: Add new check to lock_downgrade()J. R. Okajima2017-03-161-0/+3
| | | | | | | | | | | | | | | | | | | | | | | Commit: f8319483f57f ("locking/lockdep: Provide a type check for lock_is_held") didn't fully cover rwsems as downgrade_write() was left out. Introduce lock_downgrade() and use it to add new checks. See-also: http://marc.info/?l=linux-kernel&m=148581164003149&w=2 Originally-written-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1486053497-9948-3-git-send-email-hooanon05g@gmail.com [ Rewrote the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/lockdep: Provide a type check for lock_is_heldPeter Zijlstra2016-11-301-2/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | Christoph requested lockdep_assert_held() variants that distinguish between held-for-read or held-for-write. Provide: int lock_is_held_type(struct lockdep_map *lock, int read) which takes the same argument as lock_acquire(.read) and matches it to the held_lock instance. Use of this function should be gated by the debug_locks variable. When that is 0 the return value of the lock_is_held_type() function is undefined. This is done to allow both negative and positive tests for holding locks. By default we provide (positive) lockdep_assert_held{,_exclusive,_read}() macros. Requested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Jens Axboe <axboe@fb.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
* lockdep: make MAX_LOCKDEP_SUBCLASSES unconditionally visibleBartosz Golaszewski2016-09-241-2/+2
| | | | | | | | | | | This define is needed by i2c_adapter_depth() to detect if we don't exceed the maximum number of lock subclasses. Make it visible even if lockdep is disabled. Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Acked-by: Peter Rosin <peda@axentia.se> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2016-05-161-6/+17
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - massive CPU hotplug rework (Thomas Gleixner) - improve migration fairness (Peter Zijlstra) - CPU load calculation updates/cleanups (Yuyang Du) - cpufreq updates (Steve Muckle) - nohz optimizations (Frederic Weisbecker) - switch_mm() micro-optimization on x86 (Andy Lutomirski) - ... lots of other enhancements, fixes and cleanups. * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (66 commits) ARM: Hide finish_arch_post_lock_switch() from modules sched/core: Provide a tsk_nr_cpus_allowed() helper sched/core: Use tsk_cpus_allowed() instead of accessing ->cpus_allowed sched/loadavg: Fix loadavg artifacts on fully idle and on fully loaded systems sched/fair: Correct unit of load_above_capacity sched/fair: Clean up scale confusion sched/nohz: Fix affine unpinned timers mess sched/fair: Fix fairness issue on migration sched/core: Kill sched_class::task_waking to clean up the migration logic sched/fair: Prepare to fix fairness problems on migration sched/fair: Move record_wakee() sched/core: Fix comment typo in wake_q_add() sched/core: Remove unused variable sched: Make hrtick_notifier an explicit call sched/fair: Make ilb_notifier an explicit call sched/hotplug: Make activate() the last hotplug step sched/hotplug: Move migration CPU_DYING to sched_cpu_dying() sched/migration: Move CPU_ONLINE into scheduler state sched/migration: Move calc_load_migrate() into CPU_DYING sched/migration: Move prepare transition to SCHED_STARTING state ...
| * Merge branch 'sched/urgent' into sched/core to pick up fixesIngo Molnar2016-05-121-3/+5
| |\ | | | | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | locking/lockdep, sched/core: Implement a better lock pinning schemePeter Zijlstra2016-05-051-6/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The problem with the existing lock pinning is that each pin is of value 1; this mean you can simply unpin if you know its pinned, without having any extra information. This scheme generates a random (16 bit) cookie for each pin and requires this same cookie to unpin. This means you have to keep the cookie in context. No objsize difference for !LOCKDEP kernels. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | Merge branch 'locking-rwsem-for-linus' of ↵Linus Torvalds2016-05-161-0/+15
|\ \ \ | |_|/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull support for killable rwsems from Ingo Molnar: "This, by Michal Hocko, implements down_write_killable(). The main usecase will be to update mm_sem usage sites to use this new API, to allow the mm-reaper introduced in commit aac453635549 ("mm, oom: introduce oom reaper") to tear down oom victim address spaces asynchronously with minimum latencies and without deadlock worries" [ The vfs will want it too as the inode lock is changed from a mutex to a rwsem due to the parallel lookup and readdir updates ] * 'locking-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rwsem: Fix comment on register clobbering locking/rwsem: Fix down_write_killable() locking/rwsem, x86: Add frame annotation for call_rwsem_down_write_failed_killable() locking/rwsem: Provide down_write_killable() locking/rwsem, x86: Provide __down_write_killable() locking/rwsem, s390: Provide __down_write_killable() locking/rwsem, ia64: Provide __down_write_killable() locking/rwsem, alpha: Provide __down_write_killable() locking/rwsem: Introduce basis for down_write_killable() locking/rwsem, sparc: Drop superfluous arch specific implementation locking/rwsem, sh: Drop superfluous arch specific implementation locking/rwsem, xtensa: Drop superfluous arch specific implementation locking/rwsem: Drop explicit memory barriers locking/rwsem: Get rid of __down_write_nested()
| * | locking/rwsem: Provide down_write_killable()Michal Hocko2016-04-221-0/+15
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that all the architectures implement the necessary glue code we can introduce down_write_killable(). The only difference wrt. regular down_write() is that the slow path waits in TASK_KILLABLE state and the interruption by the fatal signal is reported as -EINTR to the caller. Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Zankel <chris@zankel.net> Cc: David S. Miller <davem@davemloft.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Signed-off-by: Jason Low <jason.low2@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: linux-xtensa@linux-xtensa.org Cc: sparclinux@vger.kernel.org Link: http://lkml.kernel.org/r/1460041951-22347-12-git-send-email-mhocko@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | lockdep: Fix lock_chain::base sizePeter Zijlstra2016-04-231-3/+5
|/ | | | | | | | | | | | | | | | | | | | | | | | | lock_chain::base is used to store an index into the chain_hlocks[] array, however that array contains more elements than can be indexed using the u16. Change the lock_chain structure to use a bitfield to encode the data it needs and add BUILD_BUG_ON() assertions to check the fields are wide enough. Also, for DEBUG_LOCKDEP, assert that we don't run out of elements of that array; as that would wreck the collision detectoring. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alfredo Alvarez Fernandez <alfredoalvarezfernandez@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160330093659.GS3408@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/lockdep: Eliminate lockdep_init()Andrey Ryabinin2016-02-091-2/+0
| | | | | | | | | | | | | | | Lockdep is initialized at compile time now. Get rid of lockdep_init(). Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Krinkin <krinkin.m.u@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Cc: mm-commits@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/lockdep: Convert hash tables to hlistsAndrew Morton2016-02-091-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mike said: : CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i.e. : kernel with CONFIG_UBSAN_ALIGNMENT=y fails to load without even any error : message. : : The problem is that ubsan callbacks use spinlocks and might be called : before lockdep is initialized. Particularly this line in the : reserve_ebda_region function causes problem: : : lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); : : If i put lockdep_init() before reserve_ebda_region call in : x86_64_start_reservations kernel loads well. Fix this ordering issue permanently: change lockdep so that it uses hlists for the hash tables. Unlike a list_head, an hlist_head is in its initialized state when it is all-zeroes, so lockdep is ready for operation immediately upon boot - lockdep_init() need not have run. The patch will also save some memory. Probably lockdep_init() and lockdep_initialized can be done away with now. Suggested-by: Mike Krinkin <krinkin.m.u@gmail.com> Reported-by: Mike Krinkin <krinkin.m.u@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Cc: mm-commits@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* treewide: Remove old email addressPeter Zijlstra2015-11-231-1/+1
| | | | | | | | | | | | | | | | | There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'sched-hrtimers-for-linus' of ↵Linus Torvalds2015-06-241-0/+10
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Thomas Gleixner: "This series of scheduler updates depends on sched/core and timers/core branches, which are already in your tree: - Scheduler balancing overhaul to plug a hard to trigger race which causes an oops in the balancer (Peter Zijlstra) - Lockdep updates which are related to the balancing updates (Peter Zijlstra)" * 'sched-hrtimers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched,lockdep: Employ lock pinning lockdep: Implement lock pinning lockdep: Simplify lock_release() sched: Streamline the task migration locking a little sched: Move code around sched,dl: Fix sched class hopping CBS hole sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks sched,dl: Remove return value from pull_dl_task() sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks sched,rt: Remove return value from pull_rt_task() sched: Allow balance callbacks for check_class_changed() sched: Use replace normalize_task() with __sched_setscheduler() sched: Replace post_schedule with a balance callback list
| * lockdep: Implement lock pinningPeter Zijlstra2015-06-191-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a lockdep annotation that WARNs if you 'accidentially' unlock a lock. This is especially helpful for code with callbacks, where the upper layer assumes a lock remains taken but a lower layer thinks it maybe can drop and reacquire the lock. By unwittingly breaking up the lock, races can be introduced. Lock pinning is a lockdep annotation that helps with this, when you lockdep_pin_lock() a held lock, any unlock without a lockdep_unpin_lock() will produce a WARN. Think of this as a relative of lockdep_assert_held(), except you don't only assert its held now, but ensure it stays held until you release your assertion. RFC: a possible alternative API would be something like: int cookie = lockdep_pin_lock(&foo); ... lockdep_unpin_lock(&foo, cookie); Where we pick a random number for the pin_count; this makes it impossible to sneak a lock break in without also passing the right cookie along. I've not done this because it ends up generating code for !LOCKDEP, esp. if you need to pass the cookie around for some reason. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: oleg@redhat.com Cc: wanpeng.li@linux.intel.com Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124743.906731065@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | locking/lockdep: Remove hard coded array size dependencyGeorge Beshers2015-06-191-2/+2
|/ | | | | | | | | | | | | | | | | | | | | | An apparent oversight left a hardcoded '4' in place when LOCKSTAT_POINTS was introduced. The contention_point[] and contending_point[] arrays in the structs lock_class and lock_class_stats need to be the same size for the loops in lock_stats() to be correct. This patch allows LOCKSTAT_POINTS to be changed without affecting the correctness of the code. Signed-off-by: George Beshers <gbeshers@sgi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* rcu: Improve diagnostics for blocked critical sections in irqPaul E. McKenney2015-03-031-1/+6
| | | | | | | | | | | | | | If an RCU read-side critical section occurs within an interrupt handler or a softirq handler, it cannot have been preempted. Therefore, there is a check in rcu_read_unlock_special() checking for this error. However, when this check triggers, it lacks diagnostic information. This commit therefore moves rcu_read_unlock()'s lockdep annotation to follow the call to __rcu_read_unlock() and changes rcu_read_unlock_special()'s WARN_ON_ONCE() to an lockdep_rcu_suspicious() in order to locate where the offending RCU read-side critical section began. In addition, the value of the ->rcu_read_unlock_special field is printed. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* Merge branch 'locking-core-for-linus' of ↵Linus Torvalds2014-10-131-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core locking updates from Ingo Molnar: "The main updates in this cycle were: - mutex MCS refactoring finishing touches: improve comments, refactor and clean up code, reduce debug data structure footprint, etc. - qrwlock finishing touches: remove old code, self-test updates. - small rwsem optimization - various smaller fixes/cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/lockdep: Revert qrwlock recusive stuff locking/rwsem: Avoid double checking before try acquiring write lock locking/rwsem: Move EXPORT_SYMBOL() lines to follow function definition locking/rwlock, x86: Delete unused asm/rwlock.h and rwlock.S locking/rwlock, x86: Clean up asm/spinlock*.h to remove old rwlock code locking/semaphore: Resolve some shadow warnings locking/selftest: Support queued rwlock locking/lockdep: Restrict the use of recursive read_lock() with qrwlock locking/spinlocks: Always evaluate the second argument of spin_lock_nested() locking/Documentation: Update locking/mutex-design.txt disadvantages locking/Documentation: Move locking related docs into Documentation/locking/ locking/mutexes: Use MUTEX_SPIN_ON_OWNER when appropriate locking/mutexes: Refactor optimistic spinning code locking/mcs: Remove obsolete comment locking/mutexes: Document quick lock release when unlocking locking/mutexes: Standardize arguments in lock/unlock slowpaths locking: Remove deprecated smp_mb__() barriers
| * locking/lockdep: Revert qrwlock recusive stuffPeter Zijlstra2014-10-031-9/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit f0bab73cb539 ("locking/lockdep: Restrict the use of recursive read_lock() with qrwlock") changed lockdep to try and conform to the qrwlock semantics which differ from the traditional rwlock semantics. In particular qrwlock is fair outside of interrupt context, but in interrupt context readers will ignore all fairness. The problem modeling this is that read and write side have different lock state (interrupts) semantics but we only have a single representation of these. Therefore lockdep will get confused, thinking the lock can cause interrupt lock inversions. So revert it for now; the old rwlock semantics were already imperfectly modeled and the qrwlock extra won't fit either. If we want to properly fix this, I think we need to resurrect the work by Gautham did a few years ago that split the read and write state of locks: http://lwn.net/Articles/332801/ FWIW the locking selftest that would've failed (and was reported by Borislav earlier) is something like: RL(X1); /* IRQ-ON */ LOCK(A); UNLOCK(A); RU(X1); IRQ_ENTER(); RL(X1); /* IN-IRQ */ RU(X1); IRQ_EXIT(); At which point it would report that because A is an IRQ-unsafe lock we can suffer the following inversion: CPU0 CPU1 lock(A) lock(X1) lock(A) <IRQ> lock(X1) And this is 'wrong' because X1 can recurse (assuming the above lock are in fact read-lock) but lockdep doesn't know about this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Waiman Long <Waiman.Long@hp.com> Cc: ego@linux.vnet.ibm.com Cc: bp@alien8.de Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20140930132600.GA7444@worktop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * locking/lockdep: Restrict the use of recursive read_lock() with qrwlockWaiman Long2014-08-131-1/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unlike the original unfair rwlock implementation, queued rwlock will grant lock according to the chronological sequence of the lock requests except when the lock requester is in the interrupt context. Consequently, recursive read_lock calls will now hang the process if there is a write_lock call somewhere in between the read_lock calls. This patch updates the lockdep implementation to look for recursive read_lock calls. A new read state (3) is used to mark those read_lock call that cannot be recursively called except in the interrupt context. The new read state does exhaust the 2 bits available in held_lock:read bit field. The addition of any new read state in the future may require a redesign of how all those bits are squeezed together in the held_lock structure. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1407345722-61615-2-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * locking/Documentation: Move locking related docs into Documentation/locking/Davidlohr Bueso2014-08-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Specifically: Documentation/locking/lockdep-design.txt Documentation/locking/lockstat.txt Documentation/locking/mutex-design.txt Documentation/locking/rt-mutex-design.txt Documentation/locking/rt-mutex.txt Documentation/locking/spinlocks.txt Documentation/locking/ww-mutex-design.txt Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: jason.low2@hp.com Cc: aswin@hp.com Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Mason <clm@fb.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: David Airlie <airlied@linux.ie> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David S. Miller <davem@davemloft.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jason Low <jason.low2@hp.com> Cc: Josef Bacik <jbacik@fusionio.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lubomir Rintel <lkundrak@v3.sk> Cc: Masanari Iida <standby24x7@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: fengguang.wu@intel.com Link: http://lkml.kernel.org/r/1406752916-3341-6-git-send-email-davidlohr@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-10-131-0/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - changes related to No-CBs CPUs and NO_HZ_FULL - RCU-tasks implementation - torture-test updates - miscellaneous fixes - locktorture updates - RCU documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) workqueue: Use cond_resched_rcu_qs macro workqueue: Add quiescent state between work items locktorture: Cleanup header usage locktorture: Cannot hold read and write lock locktorture: Fix __acquire annotation for spinlock irq locktorture: Support rwlocks rcu: Eliminate deadlock between CPU hotplug and expedited grace periods locktorture: Document boot/module parameters rcutorture: Rename rcutorture_runnable parameter locktorture: Add test scenario for rwsem_lock locktorture: Add test scenario for mutex_lock locktorture: Make torture scripting account for new _runnable name locktorture: Introduce torture context locktorture: Support rwsems locktorture: Add infrastructure for torturing read locks torture: Address race in module cleanup locktorture: Make statistics generic locktorture: Teach about lock debugging locktorture: Support mutexes locktorture: Add documentation ...
| * | rcu: Eliminate deadlock between CPU hotplug and expedited grace periodsPaul E. McKenney2014-09-181-0/+1
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the expedited grace-period primitives do get_online_cpus(). This greatly simplifies their implementation, but means that calls to them holding locks that are acquired by CPU-hotplug notifiers (to say nothing of calls to these primitives from CPU-hotplug notifiers) can deadlock. But this is starting to become inconvenient, as can be seen here: https://lkml.org/lkml/2014/8/5/754. The problem in this case is that some developers need to acquire a mutex from a CPU-hotplug notifier, but also need to hold it across a synchronize_rcu_expedited(). As noted above, this currently results in deadlock. This commit avoids the deadlock and retains the simplicity by creating a try_get_online_cpus(), which returns false if the get_online_cpus() reference count could not immediately be incremented. If a call to try_get_online_cpus() returns true, the expedited primitives operate as before. If a call returns false, the expedited primitives fall back to normal grace-period operations. This falling back of course results in increased grace-period latency, but only during times when CPU hotplug operations are actually in flight. The effect should therefore be negligible during normal operation. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Tested-by: Lan Tianyu <tianyu.lan@intel.com>
* | locking: Add WARN_ON_ONCE lock assertionPeter Hurley2014-09-231-0/+5
|/ | | | | | | | | | An interface may need to assert a lock invariant and not flood the system logs; add a lockdep helper macro equivalent to lockdep_assert_held() which only WARNs once. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge branch 'x86-asmlinkage-for-linus' of ↵Linus Torvalds2014-03-311-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 LTO changes from Peter Anvin: "More infrastructure work in preparation for link-time optimization (LTO). Most of these changes is to make sure symbols accessed from assembly code are properly marked as visible so the linker doesn't remove them. My understanding is that the changes to support LTO are still not upstream in binutils, but are on the way there. This patchset should conclude the x86-specific changes, and remaining patches to actually enable LTO will be fed through the Kbuild tree (other than keeping up with changes to the x86 code base, of course), although not necessarily in this merge window" * 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) Kbuild, lto: Handle basic LTO in modpost Kbuild, lto: Disable LTO for asm-offsets.c Kbuild, lto: Add a gcc-ld script to let run gcc as ld Kbuild, lto: add ld-version and ld-ifversion macros Kbuild, lto: Drop .number postfixes in modpost Kbuild, lto, workaround: Don't warn for initcall_reference in modpost lto: Disable LTO for sys_ni lto: Handle LTO common symbols in module loader lto, workaround: Add workaround for initcall reordering lto: Make asmlinkage __visible x86, lto: Disable LTO for the x86 VDSO initconst, x86: Fix initconst mistake in ts5500 code initconst: Fix initconst mistake in dcdbas asmlinkage: Make trace_hardirqs_on/off_caller visible asmlinkage, x86: Fix 32bit memcpy for LTO asmlinkage Make __stack_chk_failed and memcmp visible asmlinkage: Mark rwsem functions that can be called from assembler asmlinkage asmlinkage: Make main_extable_sort_needed visible asmlinkage, mutex: Mark __visible asmlinkage: Make trace_hardirq visible ...
| * asmlinkage: Make lockdep_sys_exit asmlinkageAndi Kleen2014-02-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | lockdep_sys_exit can be called from assembler code, so make it asmlinkage. Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/1391845930-28580-5-git-send-email-ak@linux.intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* | lockdep: Change lockdep_set_novalidate_class() to use _and_nameOleg Nesterov2014-02-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cosmetic. This doesn't really matter because a) device->mutex is the only user of __lockdep_no_validate__ and b) this class should be never reported as the source of problem, but if something goes wrong "&dev->mutex" looks better than "&__lockdep_no_validate__" as the name of the lock. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140120182016.GA26512@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | lockdep: Make held_lock->check and "int check" argument boolOleg Nesterov2014-02-091-16/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | The "int check" argument of lock_acquire() and held_lock->check are misleading. This is actually a boolean: 2 means "true", everything else is "false". And there is no need to pass 1 or 0 to lock_acquire() depending on CONFIG_PROVE_LOCKING, __lock_acquire() checks prove_locking at the start and clears "check" if !CONFIG_PROVE_LOCKING. Note: probably we can simply kill this member/arg. The only explicit user of check => 0 is rcu_lock_acquire(), perhaps we can change it to use lock_acquire(trylock =>, read => 2). __lockdep_no_validate means check => 0 implicitly, but we can change validate_chain() to check hlock->instance->key instead. Not to mention it would be nice to get rid of lockdep_set_novalidate_class(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140120182006.GA26495@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* seqcount: Add lockdep functionality to seqcount/seqlock structuresJohn Stultz2013-11-061-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently seqlocks and seqcounts don't support lockdep. After running across a seqcount related deadlock in the timekeeping code, I used a less-refined and more focused variant of this patch to narrow down the cause of the issue. This is a first-pass attempt to properly enable lockdep functionality on seqlocks and seqcounts. Since seqcounts are used in the vdso gettimeofday code, I've provided non-lockdep accessors for those needs. I've also handled one case where there were nested seqlock writers and there may be more edge cases. Comments and feedback would be appreciated! Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: netdev@vger.kernel.org Link: http://lkml.kernel.org/r/1381186321-4906-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* lockdep: Introduce lock_acquire_exclusive()/shared() helper macrosMichel Lespinasse2013-07-121-69/+23
| | | | | | | | | | | | | | | | | | | | | | | | In lockdep.h, the spinlock/mutex/rwsem/rwlock/lock_map acquire macros have different definitions based on the value of CONFIG_PROVE_LOCKING. We have separate ifdefs for each of these definitions, which seems redundant. Introduce lock_acquire_{exclusive,shared,shared_recursive} helpers which will have different definitions based on CONFIG_PROVE_LOCKING. Then all other helper macros can be defined based on the above ones, which reduces the amount of ifdefined code. Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@linux.intel.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130708212350.6DD1931C15E@corp2gmr1-1.hot.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'core-locking-for-linus' of ↵Linus Torvalds2013-02-221-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core locking changes from Ingo Molnar: "The biggest change is the rwsem lock-steal improvements, both to the assembly optimized and the spinlock based variants. The other notable change is the clean up of the seqlock implementation to be based on the seqcount infrastructure. The rest is assorted smaller debuggability, cleanup and continued -rt locking changes." * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rwsem-spinlock: Implement writer lock-stealing for better scalability futex: Revert "futex: Mark get_robust_list as deprecated" generic: Use raw local irq variant for generic cmpxchg lockdep: Selftest: convert spinlock to raw spinlock seqlock: Use seqcount infrastructure seqlock: Remove unused functions ntp: Make ntp_lock raw intel_idle: Convert i7300_idle_lock to raw_spinlock locking: Various static lock initializer fixes lockdep: Print more info when MAX_LOCK_DEPTH is exceeded rwsem: Implement writer lock-stealing for better scalability lockdep: Silence warning if CONFIG_LOCKDEP isn't set watchdog: Use local_clock for get_timestamp() lockdep: Rename print_unlock_inbalance_bug() to print_unlock_imbalance_bug() locking/stat: Fix a typo
| * lockdep: Silence warning if CONFIG_LOCKDEP isn't setPaul Bolle2013-02-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit c9a4962881929df7f1ef6e63e1b9da304faca4dd ("nfsd: make client_lock per net") compiling nfs4state.o without CONFIG_LOCKDEP set, triggers this GCC warning: fs/nfsd/nfs4state.c: In function ‘free_client’: fs/nfsd/nfs4state.c:1051:19: warning: unused variable ‘nn’ [-Wunused-variable] The cause of that warning is that lockdep_assert_held() compiles away if CONFIG_LOCKDEP is not set. Silence this warning by using the argument to lockdep_assert_held() as a nop if CONFIG_LOCKDEP is not set. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: J. Bruce Fields <bfields@redhat.com> Link: http://lkml.kernel.org/r/1359060797.1325.33.camel@x61.thuisdomein Signed-off-by: Ingo Molnar <mingo@kernel.org> -- include/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
* | lockdep: make lockdep_assert_held() not have a return valueJohannes Berg2013-02-211-1/+3
|/ | | | | | | | | | | | | | | | | | | I recently made the mistake of writing: foo = lockdep_dereference_protected(..., lockdep_assert_held(...)); which is clearly bogus. If lockdep is disabled in the config this would cause a compile failure, if it is enabled then it compiles and causes a puzzling warning about dereferencing without the correct protection. Wrap the macro in "do { ... } while (0)" to also fail compile for this when lockdep is enabled. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep, rwsem: provide down_write_nest_lock()Jiri Kosina2013-01-111-0/+3
| | | | | | | | | | | | | | | | | | down_write_nest_lock() provides a means to annotate locking scenario where an outer lock is guaranteed to serialize the order nested locks are being acquired. This is analogoue to already existing mutex_lock_nest_lock() and spin_lock_nest_lock(). Signed-off-by: Jiri Kosina <jkosina@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mel Gorman <mel@csn.ul.ie> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: fix oops in processing workqueuePeter Zijlstra2012-05-151-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Under memory load, on x86_64, with lockdep enabled, the workqueue's process_one_work() has been seen to oops in __lock_acquire(), barfing on a 0xffffffff00000000 pointer in the lockdep_map's class_cache[]. Because it's permissible to free a work_struct from its callout function, the map used is an onstack copy of the map given in the work_struct: and that copy is made without any locking. Surprisingly, gcc (4.5.1 in Hugh's case) uses "rep movsl" rather than "rep movsq" for that structure copy: which might race with a workqueue user's wait_on_work() doing lock_map_acquire() on the source of the copy, putting a pointer into the class_cache[], but only in time for the top half of that pointer to be copied to the destination map. Boom when process_one_work() subsequently does lock_map_acquire() on its onstack copy of the lockdep_map. Fix this, and a similar instance in call_timer_fn(), with a lockdep_copy_map() function which additionally NULLs the class_cache[]. Note: this oops was actually seen on 3.4-next, where flush_work() newly does the racing lock_map_acquire(); but Tejun points out that 3.4 and earlier are already vulnerable to the same through wait_on_work(). * Patch orginally from Peter. Hugh modified it a bit and wrote the description. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Reported-by: Hugh Dickins <hughd@google.com> LKML-Reference: <alpine.LSU.2.00.1205070951170.1544@eggly.anvils> Signed-off-by: Tejun Heo <tj@kernel.org>
* printk, lockdep: Disable lock debugging on zap_locks()Peter Zijlstra2011-11-141-0/+4
| | | | | | | | | | | | | zap_locks() is used by printk() in a last ditch effort to get data out, clearly we cannot trust lock state after this so make it disable lock debugging. Also don't treat printk recursion through lockdep as a normal recursion bug but try hard to get the lockdep splat out. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-kqxwmo4xz37e1s8w0xopvr0q@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Restore checks for blocking in RCU read-side critical sectionsPaul E. McKenney2011-09-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Long ago, using TREE_RCU with PREEMPT would result in "scheduling while atomic" diagnostics if you blocked in an RCU read-side critical section. However, PREEMPT now implies TREE_PREEMPT_RCU, which defeats this diagnostic. This commit therefore adds a replacement diagnostic based on PROVE_RCU. Because rcu_lockdep_assert() and lockdep_rcu_dereference() are now being used for things that have nothing to do with rcu_dereference(), rename lockdep_rcu_dereference() to lockdep_rcu_suspicious() and add a third argument that is a string indicating what is suspicious. This third argument is passed in from a new third argument to rcu_lockdep_assert(). Update all calls to rcu_lockdep_assert() to add an informative third argument. Also, add a pair of rcu_lockdep_assert() calls from within rcu_note_context_switch(), one complaining if a context switch occurs in an RCU-bh read-side critical section and another complaining if a context switch occurs in an RCU-sched read-side critical section. These are present only if the PROVE_RCU kernel parameter is enabled. Finally, fix some checkpatch whitespace complaints in lockdep.c. Again, you must enable PROVE_RCU to see these new diagnostics. But you are enabling PROVE_RCU to check out new RCU uses in any case, aren't you? Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* lockdep, mutex: provide mutex_lock_nest_lockPeter Zijlstra2011-05-251-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to convert i_mmap_lock to a mutex we need a mutex equivalent to spin_lock_nest_lock(), thus provide the mutex_lock_nest_lock() annotation. As with spin_lock_nest_lock(), mutex_lock_nest_lock() allows annotation of the locking pattern where an outer lock serializes the acquisition order of nested locks. That is, if every time you lock multiple locks A, say A1 and A2 you first acquire N, the order of acquiring A1 and A2 is irrelevant. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'fixes-2.6.38' of ↵Linus Torvalds2011-01-211-0/+3
|\ | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq * 'fixes-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: note the nested NOT_RUNNING test in worker_clr_flags() isn't a noop workqueue: relax lockdep annotation on flush_work()
| * workqueue: relax lockdep annotation on flush_work()Tejun Heo2011-01-111-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the lockdep annotation in flush_work() requires exclusive access on the workqueue the target work is queued on and triggers warning if a work is trying to flush another work on the same workqueue; however, this is no longer true as workqueues can now execute multiple works concurrently. This patch adds lock_map_acquire_read() and make process_one_work() hold read access to the workqueue while executing a work and start_flush_work() check for write access if concurrnecy level is one or the workqueue has a rescuer (as only one execution resource - the rescuer - is guaranteed to be available under memory pressure), and read access if higher. This better represents what's going on and removes spurious lockdep warnings which are triggered by fake dependency chain created through flush_work(). * Peter pointed out that flushing another work from a WQ_MEM_RECLAIM wq breaks forward progress guarantee under memory pressure. Condition check accordingly updated. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: "Rafael J. Wysocki" <rjw@sisk.pl> Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@kernel.org
* | lockdep: Move early boot local IRQ enable/disable status to init/main.cTejun Heo2011-01-201-8/+0
|/ | | | | | | | | | | | | | | | | | | | | | During early boot, local IRQ is disabled until IRQ subsystem is properly initialized. During this time, no one should enable local IRQ and some operations which usually are not allowed with IRQ disabled, e.g. operations which might sleep or require communications with other processors, are allowed. lockdep tracked this with early_boot_irqs_off/on() callbacks. As other subsystems need this information too, move it to init/main.c and make it generally available. While at it, toggle the boolean to early_boot_irqs_disabled instead of enabled so that it can be initialized with %false and %true indicates the exceptional condition. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <20110120110635.GB6036@htj.dyndns.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'irq-core-for-linus' of ↵Linus Torvalds2010-10-211-8/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (96 commits) apic, x86: Use BIOS settings for IBS and MCE threshold interrupt LVT offsets apic, x86: Check if EILVT APIC registers are available (AMD only) x86: ioapic: Call free_irte only if interrupt remapping enabled arm: Use ARCH_IRQ_INIT_FLAGS genirq, ARM: Fix boot on ARM platforms genirq: Fix CONFIG_GENIRQ_NO_DEPRECATED=y build x86: Switch sparse_irq allocations to GFP_KERNEL genirq: Switch sparse_irq allocator to GFP_KERNEL genirq: Make sparse_lock a mutex x86: lguest: Use new irq allocator genirq: Remove the now unused sparse irq leftovers genirq: Sanitize dynamic irq handling genirq: Remove arch_init_chip_data() x86: xen: Sanitise sparse_irq handling x86: Use sane enumeration x86: uv: Clean up the direct access to irq_desc x86: Make io_apic.c local functions static genirq: Remove irq_2_iommu x86: Speed up the irq_remapped check in hot pathes intr_remap: Simplify the code further ... Fix up trivial conflicts in arch/x86/Kconfig
| * genirq: Remove early_init_irq_lock_class()Thomas Gleixner2010-10-121-8/+0
| | | | | | | | | | | | | | | | | | | | early_init_irq_lock_class() is called way before anything touches the irq descriptors. In case of SPARSE_IRQ=y this is a NOP operation because the radix tree is empty at this point. For the SPARSE_IRQ=n case it's sufficient to set the lock class in early_init_irq(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@elte.hu>
* | lockdep: Add improved subclass cachingHitoshi Mitake2010-10-181-1/+12
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current lockdep_map only caches one class with subclass == 0, and looks up hash table of classes when subclass != 0. It seems that this has no problem because the case of subclass != 0 is rare. But locks of struct rq are acquired with subclass == 1 when task migration is executed. Task migration is high frequent event, so I modified lockdep to cache subclasses. I measured the score of perf bench sched messaging. This patch has slightly but certain (order of milli seconds or 10 milli seconds) effect when lots of tasks are running. I'll show the result in the tail of this description. NR_LOCKDEP_CACHING_CLASSES specifies how many classes can be cached in the instances of lockdep_map. I discussed with Peter Zijlstra in LinuxCon Japan about this approach and he taught me that caching every subclasses(8) is cleary waste of memory. So number of cached classes should be configurable. === Score comparison of benchmarks === # "min" means best score, and "max" means worst score for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done before: min: 0.565000, max: 0.583000, avg: 0.572500 after: min: 0.559000, max: 0.568000, avg: 0.563300 # with more processes for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done before: min: 2.274000, max: 2.298000, avg: 2.286300 after: min: 2.242000, max: 2.270000, avg: 2.259700 Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286269311-28336-2-git-send-email-mitake@dcl.info.waseda.ac.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: Add novalidate class for dev->mutex conversionPeter Zijlstra2010-05-211-0/+8
| | | | | | | | | | | | | | | | The conversion of device->sem to device->mutex resulted in lockdep warnings. Create a novalidate class for now until the driver folks come up with separate classes. That way we have at least the basic mutex debugging coverage. Add a checkpatch error so the usage is reserved for device->mutex. [ tglx: checkpatch and compile fix for LOCKDEP=n ] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* sysctl extern cleanup: lockdepDave Young2010-03-121-0/+4
| | | | | | | | | | | | | | Extern declarations in sysctl.c should be moved to their own header file, and then include them in relavant .c files. Move lockdep extern declarations to linux/lockdep.h Signed-off-by: Dave Young <hidave.darkstar@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* rcu: Integrate rcu_dereference_check() message into lockdepPaul E. McKenney2010-02-251-0/+4
| | | | | | | | | | | | | | | | | | | Make rcu_dereference_check() print the list of held locks in addition to the stack dump to ease debugging. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-3-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: Reintroduce generation count to make BFS fasterMing Lei2009-08-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We still can apply DaveM's generation count optimization to BFS, based on the following idea: - before doing each BFS, increase the global generation id by 1 - if one node in the graph has been visited, mark it as visited by storing the current global generation id into the node's dep_gen_id field - so we can decide if one node has been visited already, by comparing the node's dep_gen_id with the global generation id. By applying DaveM's generation count optimization to current implementation of BFS, we gain the following advantages: - we save MAX_LOCKDEP_ENTRIES/8 bytes memory; - we remove the bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES); in each BFS, which is very time-consuming since MAX_LOCKDEP_ENTRIES may be very large.(16384UL) Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "David S. Miller" <davem@davemloft.net> LKML-Reference: <1248274089-6358-1-git-send-email-tom.leiming@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: Deal with many similar locksPeter Zijlstra2009-08-021-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | spin_lock_nest_lock() allows to take many instances of the same class, this can easily lead to overflow of MAX_LOCK_DEPTH. To avoid this overflow, we'll stop accounting instances but start reference counting the class in the held_lock structure. [ We could maintain a list of instances, if we'd move the hlock stuff into __lock_acquired(), but that would require significant modifications to the current code. ] We restrict this mode to spin_lock_nest_lock() only, because it degrades the lockdep quality due to lost of instance. For lockstat this means we don't track lock statistics for any but the first lock in the series. Currently nesting is limited to 11 bits because that was the spare space available in held_lock. This yields a 2048 instances maximium. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: Introduce lockdep_assert_held()Peter Zijlstra2009-08-021-0/+8
| | | | | | | | Add a lockdep helper to validate that we indeed are the owner of a lock. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: BFS cleanupPeter Zijlstra2009-07-241-4/+3
| | | | | | | | | | | | | | Some cleanups of the lockdep code after the BFS series: - Remove the last traces of the generation id - Fixup comment style - Move the bfs routines into lockdep.c - Cleanup the bfs routines [ tom.leiming@gmail.com: Fix crash ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1246201486-7308-11-git-send-email-tom.leiming@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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