Commit-ID: 70207686e492fb97c11d88ae7d8ebce7d2d080aa Gitweb: http://git.kernel.org/tip/70207686e492fb97c11d88ae7d8ebce7d2d080aa Author: Chris Wilson <ch...@chris-wilson.co.uk> AuthorDate: Thu, 1 Dec 2016 11:47:08 +0000 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Sat, 14 Jan 2017 11:37:16 +0100
locking/ww_mutex: Add kselftests for ww_mutex ABBA deadlock detection Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Maarten Lankhorst <d...@mblankhorst.nl> Cc: Nicolai Hähnle <nhaeh...@gmail.com> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/20161201114711.28697-6-ch...@chris-wilson.co.uk Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/locking/test-ww_mutex.c | 98 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c index 835fa7a..5a643ba 100644 --- a/kernel/locking/test-ww_mutex.c +++ b/kernel/locking/test-ww_mutex.c @@ -153,6 +153,96 @@ out: return ret; } +struct test_abba { + struct work_struct work; + struct ww_mutex a_mutex; + struct ww_mutex b_mutex; + struct completion a_ready; + struct completion b_ready; + bool resolve; + int result; +}; + +static void test_abba_work(struct work_struct *work) +{ + struct test_abba *abba = container_of(work, typeof(*abba), work); + struct ww_acquire_ctx ctx; + int err; + + ww_acquire_init(&ctx, &ww_class); + ww_mutex_lock(&abba->b_mutex, &ctx); + + complete(&abba->b_ready); + wait_for_completion(&abba->a_ready); + + err = ww_mutex_lock(&abba->a_mutex, &ctx); + if (abba->resolve && err == -EDEADLK) { + ww_mutex_unlock(&abba->b_mutex); + ww_mutex_lock_slow(&abba->a_mutex, &ctx); + err = ww_mutex_lock(&abba->b_mutex, &ctx); + } + + if (!err) + ww_mutex_unlock(&abba->a_mutex); + ww_mutex_unlock(&abba->b_mutex); + ww_acquire_fini(&ctx); + + abba->result = err; +} + +static int test_abba(bool resolve) +{ + struct test_abba abba; + struct ww_acquire_ctx ctx; + int err, ret; + + ww_mutex_init(&abba.a_mutex, &ww_class); + ww_mutex_init(&abba.b_mutex, &ww_class); + INIT_WORK_ONSTACK(&abba.work, test_abba_work); + init_completion(&abba.a_ready); + init_completion(&abba.b_ready); + abba.resolve = resolve; + + schedule_work(&abba.work); + + ww_acquire_init(&ctx, &ww_class); + ww_mutex_lock(&abba.a_mutex, &ctx); + + complete(&abba.a_ready); + wait_for_completion(&abba.b_ready); + + err = ww_mutex_lock(&abba.b_mutex, &ctx); + if (resolve && err == -EDEADLK) { + ww_mutex_unlock(&abba.a_mutex); + ww_mutex_lock_slow(&abba.b_mutex, &ctx); + err = ww_mutex_lock(&abba.a_mutex, &ctx); + } + + if (!err) + ww_mutex_unlock(&abba.b_mutex); + ww_mutex_unlock(&abba.a_mutex); + ww_acquire_fini(&ctx); + + flush_work(&abba.work); + destroy_work_on_stack(&abba.work); + + ret = 0; + if (resolve) { + if (err || abba.result) { + pr_err("%s: failed to resolve ABBA deadlock, A err=%d, B err=%d\n", + __func__, err, abba.result); + ret = -EINVAL; + } + } else { + if (err != -EDEADLK && abba.result != -EDEADLK) { + pr_err("%s: missed ABBA deadlock, A err=%d, B err=%d\n", + __func__, err, abba.result); + ret = -EINVAL; + } + } + return ret; +} + static int __init test_ww_mutex_init(void) { int ret; @@ -165,6 +255,14 @@ static int __init test_ww_mutex_init(void) if (ret) return ret; + ret = test_abba(false); + if (ret) + return ret; + + ret = test_abba(true); + if (ret) + return ret; + return 0; }
