user/sven/linux.git/kernel/locking/locktorture.c, branch v5.7

locktorture: Forgive apparent unfairness if CPU hotplug

2020-02-20T23:59:59Z

If CPU hotplug testing is enabled, a lock might appear to be maximally unfair just because one of the CPUs was offline almost all the time. This commit therefore forgives unfairness if CPU hotplug testing was enabled. Signed-off-by: Paul E. McKenney

locktorture: Use private random-number generators

2020-02-20T23:59:59Z

Both lock_torture_writer() and lock_torture_reader() use the "static" keyword on their DEFINE_TORTURE_RANDOM(rand) declarations, which means that a single instance of a random-number generator are shared among all the writers and another is shared among all the readers. Unfortunately, this random-number generator was not designed for concurrent access. This commit therefore removes both "static" keywords so that each reader and each writer gets its own random-number generator. Signed-off-by: Paul E. McKenney

locktorture: Print ratio of acquisitions, not failures

2020-02-20T23:59:59Z

The __torture_print_stats() function in locktorture.c carefully initializes local variable "min" to statp[0].n_lock_acquired, but then compares it to statp[i].n_lock_fail. Given that the .n_lock_fail field should normally be zero, and given the initialization, it seems reasonable to display the maximum and minimum number acquisitions instead of miscomputing the maximum and minimum number of failures. This commit therefore switches from failures to acquisitions. And this turns out to be not only a day-zero bug, but entirely my own fault. I hate it when that happens! Fixes: 0af3fe1efa53 ("locktorture: Add a lock-torture kernel module") Reported-by: Will Deacon Signed-off-by: Paul E. McKenney Acked-by: Will Deacon Cc: Davidlohr Bueso Cc: Josh Triplett Cc: Peter Zijlstra

locking: locktorture: Do not include rwlock.h directly

2019-10-05T18:50:24Z

Including rwlock.h directly will cause kernel builds to fail if CONFIG_PREEMPT_RT is defined. The correct header file (rwlock_rt.h OR rwlock.h) will be included by spinlock.h which is included by locktorture.c anyway. Remove the include of linux/rwlock.h. Signed-off-by: Wolfgang M. Reimer Signed-off-by: Sebastian Andrzej Siewior Acked-by: Davidlohr Bueso Signed-off-by: Paul E. McKenney

locktorture: Replace strncmp() with str_has_prefix()

2019-10-05T18:48:38Z

The strncmp() function is error-prone because it is easy to get the length wrong, especially if the string is subject to change, especially given the need to account for the terminating nul byte. This commit therefore substitutes the newly introduced str_has_prefix(), which does not require a separately specified length. Signed-off-by: Chuhong Yuan Signed-off-by: Paul E. McKenney

torture: Allow inter-stutter interval to be specified

2019-05-28T16:06:09Z

Currently, the inter-stutter interval is the same as the stutter duration, that is, whatever number of jiffies is passed into torture_stutter_init(). This has worked well for quite some time, but the addition of forward-progress testing to rcutorture can delay processes for several seconds, which can triple the time that they are stuttered. This commit therefore adds a second argument to torture_stutter_init() that specifies the inter-stutter interval. While locktorture preserves the current behavior, rcutorture uses the RCU CPU stall warning interval to provide a wider inter-stutter interval. Signed-off-by: Paul E. McKenney

locktorture: NULL cxt.lwsa and cxt.lrsa to allow bad-arg detection

2019-03-26T21:42:53Z

Currently, lock_torture_cleanup() uses the values of cxt.lwsa and cxt.lrsa to detect bad parameters that prevented locktorture from initializing, let alone running. In this case, lock_torture_cleanup() does no cleanup aside from invoking torture_cleanup_begin() and torture_cleanup_end(), as required to permit future torture tests to run. However, this heuristic fails if the run with bad parameters was preceded by a previous run that actually ran: In this case, both cxt.lwsa and cxt.lrsa will remain non-zero, which means that the current lock_torture_cleanup() invocation will be unable to detect the fact that it should skip cleanup, which can result in charming outcomes such as double frees. This commit therefore NULLs out both cxt.lwsa and cxt.lrsa at the end of any run that actually ran. Signed-off-by: Paul E. McKenney Cc: Davidlohr Bueso Cc: Josh Triplett

Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', 'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD

2019-02-09T16:47:52Z

doc.2019.01.26a: Documentation updates. fixes.2019.01.26a: Miscellaneous fixes. sil.2019.01.26a: Removal of a few more spin_is_locked() instances. spdx.2019.02.09a: Add SPDX identifiers to RCU files srcu.2019.01.26a: SRCU updates. torture.2019.01.26a: Torture-test updates.

locking/locktorture: Convert to SPDX license identifier

2019-02-09T16:46:37Z

Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney Reviewed-by: Thomas Gleixner

rcutorture: Add grace period after CPU offline

2019-01-25T23:37:10Z

Beyond a certain point in the CPU-hotplug offline process, timers get stranded on the outgoing CPU, and won't fire until that CPU comes back online, which might well be never. This commit therefore adds a hook in torture_onoff_init() that is invoked from torture_offline(), which rcutorture uses to occasionally wait for a grace period. This should result in failures for RCU implementations that rely on stranded timers eventually firing in the absence of the CPU coming back online. Reported-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney