linux/lib/locking-selftest.c, branch v5.10

lockdep/selftest: Introduce recursion3

2020-08-26T10:42:08Z

Add a test case shows that USED_IN_*_READ and ENABLE_*_READ can cause deadlock too. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-20-boqun.feng@gmail.com

locking/selftest: Add test cases for queued_read_lock()

2020-08-26T10:42:07Z

Add two self test cases for the following case: P0: P1: P2: spin_lock_irq(&slock) read_lock(&rwlock) write_lock_irq(&rwlock) read_lock(&rwlock) spin_lock(&slock) , which is a deadlock, as the read_lock() on P0 cannot get the lock because of the fairness. P0: P1: P2: spin_lock(&slock) read_lock(&rwlock) write_lock(&rwlock) read_lock(&rwlock) spin_lock_irq(&slock) , which is not a deadlock, as the read_lock() on P0 can get the lock because it could use the unfair fastpass. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-19-boqun.feng@gmail.com

Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests"

2020-08-26T10:42:07Z

This reverts commit d82fed75294229abc9d757f08a4817febae6c4f4. Since we now could handle mixed read-write deadlock detection well, the self tests could be detected as expected, no need to use this work-around. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-18-boqun.feng@gmail.com

lockdep/selftest: Add more recursive read related test cases

2020-08-26T10:42:07Z

Add those four test cases: 1. X --(ER)--> Y --(ER)--> Z --(ER)--> X is deadlock. 2. X --(EN)--> Y --(SR)--> Z --(ER)--> X is deadlock. 3. X --(EN)--> Y --(SR)--> Z --(SN)--> X is not deadlock. 4. X --(ER)--> Y --(SR)--> Z --(EN)--> X is not deadlock. Those self testcases are valuable for the development of supporting recursive read related deadlock detection. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-17-boqun.feng@gmail.com

lockdep/selftest: Unleash irq_read_recursion2 and add more

2020-08-26T10:42:06Z

Now since we can handle recursive read related irq inversion deadlocks correctly, uncomment the irq_read_recursion2 and add more testcases. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-16-boqun.feng@gmail.com

lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior

2020-08-26T10:42:06Z

As our chain cache doesn't differ read/write locks, so even we can detect a read-lock/lock-write deadlock in check_noncircular(), we can still be fooled if a read-lock/lock-read case(which is not a deadlock) comes first. So introduce this test case to test specific to the chain cache behavior on detecting recursive read lock related deadlocks. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-14-boqun.feng@gmail.com

locking: More accurate annotations for read_lock()

2020-08-26T10:42:02Z

On the archs using QUEUED_RWLOCKS, read_lock() is not always a recursive read lock, actually it's only recursive if in_interrupt() is true. So change the annotation accordingly to catch more deadlocks. Note we used to treat read_lock() as pure recursive read locks in lib/locking-seftest.c, and this is useful, especially for the lockdep development selftest, so we keep this via a variable to force switching lock annotation for read_lock(). Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200807074238.1632519-2-boqun.feng@gmail.com

locking/lockdep: Remove unused @nested argument from lock_release()

2019-10-09T10:46:10Z

Since the following commit: b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release") @nested is no longer used in lock_release(), so remove it from all lock_release() calls and friends. Signed-off-by: Qian Cai Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Acked-by: Daniel Vetter Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: alexander.levin@microsoft.com Cc: daniel@iogearbox.net Cc: davem@davemloft.net Cc: dri-devel@lists.freedesktop.org Cc: duyuyang@gmail.com Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: intel-gfx@lists.freedesktop.org Cc: jack@suse.com Cc: jlbec@evilplan.or Cc: joonas.lahtinen@linux.intel.com Cc: joseph.qi@linux.alibaba.com Cc: jslaby@suse.com Cc: juri.lelli@redhat.com Cc: maarten.lankhorst@linux.intel.com Cc: mark@fasheh.com Cc: mhocko@kernel.org Cc: mripard@kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: rodrigo.vivi@intel.com Cc: sean@poorly.run Cc: st@kernel.org Cc: tj@kernel.org Cc: tytso@mit.edu Cc: vdavydov.dev@gmail.com Cc: vincent.guittot@linaro.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw Signed-off-by: Ingo Molnar

locking/lockdep: Make it easy to detect whether or not inside a selftest

2019-02-28T06:55:43Z

The patch that frees unused lock classes will modify the behavior of lockdep_free_key_range() and lockdep_reset_lock() depending on whether or not these functions are called from the context of the lockdep selftests. Hence make it easy to detect whether or not lockdep code is called from the context of a lockdep selftest. Signed-off-by: Bart Van Assche Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Johannes Berg Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Waiman Long Cc: Will Deacon Cc: johannes.berg@intel.com Cc: tj@kernel.org Link: https://lkml.kernel.org/r/20190214230058.196511-10-bvanassche@acm.org Signed-off-by: Ingo Molnar

locking: Implement an algorithm choice for Wound-Wait mutexes

2018-07-03T07:44:36Z

The current Wound-Wait mutex algorithm is actually not Wound-Wait but Wait-Die. Implement also Wound-Wait as a per-ww-class choice. Wound-Wait is, contrary to Wait-Die a preemptive algorithm and is known to generate fewer backoffs. Testing reveals that this is true if the number of simultaneous contending transactions is small. As the number of simultaneous contending threads increases, Wait-Wound becomes inferior to Wait-Die in terms of elapsed time. Possibly due to the larger number of held locks of sleeping transactions. Update documentation and callers. Timings using git://people.freedesktop.org/~thomash/ww_mutex_test tag patch-18-06-15 Each thread runs 100000 batches of lock / unlock 800 ww mutexes randomly chosen out of 100000. Four core Intel x86_64: Algorithm #threads Rollbacks time Wound-Wait 4 ~100 ~17s. Wait-Die 4 ~150000 ~19s. Wound-Wait 16 ~360000 ~109s. Wait-Die 16 ~450000 ~82s. Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Gustavo Padovan Cc: Maarten Lankhorst Cc: Sean Paul Cc: David Airlie Cc: Davidlohr Bueso Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Thomas Gleixner Cc: Kate Stewart Cc: Philippe Ombredanne Cc: Greg Kroah-Hartman Cc: linux-doc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Co-authored-by: Peter Zijlstra Signed-off-by: Thomas Hellstrom Acked-by: Peter Zijlstra (Intel) Acked-by: Ingo Molnar