From: "Paul E. McKenney" <[email protected]> This commit adds a locktorture.acq_writer_lim module parameter that specifies the maximum number of jiffies that is expected to be consumed by write-side lock acquisition. If this limit is exceeded, a WARN_ONCE() causes a splat. Note that this limit applies to the main lock acquisition only, not to any nested acquisitions.
Signed-off-by: Paul E. McKenney <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> --- kernel/locking/locktorture.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index c8c322e69a90..296815ef67ae 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -33,6 +33,7 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <[email protected]>"); +torture_param(int, acq_writer_lim, 0, "Write_acquisition time limit (jiffies)."); torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable"); torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)"); torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads"); @@ -852,11 +853,13 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = { */ static int lock_torture_writer(void *arg) { - struct lock_stress_stats *lwsp = arg; - int tid = lwsp - cxt.lwsa; - DEFINE_TORTURE_RANDOM(rand); + unsigned long j; + unsigned long j1; u32 lockset_mask; + struct lock_stress_stats *lwsp = arg; + DEFINE_TORTURE_RANDOM(rand); bool skip_main_lock; + int tid = lwsp - cxt.lwsa; VERBOSE_TOROUT_STRING("lock_torture_writer task started"); if (!rt_task(current)) @@ -883,12 +886,20 @@ static int lock_torture_writer(void *arg) cxt.cur_ops->nested_lock(tid, lockset_mask); if (!skip_main_lock) { + if (acq_writer_lim > 0) + j = jiffies; cxt.cur_ops->writelock(tid); if (WARN_ON_ONCE(lock_is_write_held)) lwsp->n_lock_fail++; lock_is_write_held = true; if (WARN_ON_ONCE(atomic_read(&lock_is_read_held))) lwsp->n_lock_fail++; /* rare, but... */ + if (acq_writer_lim > 0) { + j1 = jiffies; + WARN_ONCE(time_after(j1, j + acq_writer_lim), + "%s: Lock acquisition took %lu jiffies.\n", + __func__, j1 - j); + } lwsp->n_lock_acquired++; cxt.cur_ops->write_delay(&rand); -- 2.34.1
