From 8c52cca04f97a4c09ec2f0bd8fe6d0cdf49834e4 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Thu, 18 Mar 2021 13:28:14 -0400 Subject: locking/locktorture: Fix incorrect use of ww_acquire_ctx in ww_mutex test The ww_acquire_ctx structure for ww_mutex needs to persist for a complete lock/unlock cycle. In the ww_mutex test in locktorture, however, both ww_acquire_init() and ww_acquire_fini() are called within the lock function only. This causes a lockdep splat of "WARNING: Nested lock was not taken" when lockdep is enabled in the kernel. To fix this problem, we need to move the ww_acquire_fini() after the ww_mutex_unlock() in torture_ww_mutex_unlock(). This is done by allocating a global array of ww_acquire_ctx structures. Each locking thread is associated with its own ww_acquire_ctx via the unique thread id it has so that both the lock and unlock functions can access the same ww_acquire_ctx structure. Signed-off-by: Waiman Long Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210318172814.4400-6-longman@redhat.com --- kernel/locking/locktorture.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) (limited to 'kernel/locking') diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 90a975a95a13..b3adb40549bf 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -374,15 +374,27 @@ static struct lock_torture_ops mutex_lock_ops = { */ static DEFINE_WD_CLASS(torture_ww_class); static struct ww_mutex torture_ww_mutex_0, torture_ww_mutex_1, torture_ww_mutex_2; +static struct ww_acquire_ctx *ww_acquire_ctxs; static void torture_ww_mutex_init(void) { ww_mutex_init(&torture_ww_mutex_0, &torture_ww_class); ww_mutex_init(&torture_ww_mutex_1, &torture_ww_class); ww_mutex_init(&torture_ww_mutex_2, &torture_ww_class); + + ww_acquire_ctxs = kmalloc_array(cxt.nrealwriters_stress, + sizeof(*ww_acquire_ctxs), + GFP_KERNEL); + if (!ww_acquire_ctxs) + VERBOSE_TOROUT_STRING("ww_acquire_ctx: Out of memory"); +} + +static void torture_ww_mutex_exit(void) +{ + kfree(ww_acquire_ctxs); } -static int torture_ww_mutex_lock(int tid __maybe_unused) +static int torture_ww_mutex_lock(int tid) __acquires(torture_ww_mutex_0) __acquires(torture_ww_mutex_1) __acquires(torture_ww_mutex_2) @@ -392,7 +404,7 @@ __acquires(torture_ww_mutex_2) struct list_head link; struct ww_mutex *lock; } locks[3], *ll, *ln; - struct ww_acquire_ctx ctx; + struct ww_acquire_ctx *ctx = &ww_acquire_ctxs[tid]; locks[0].lock = &torture_ww_mutex_0; list_add(&locks[0].link, &list); @@ -403,12 +415,12 @@ __acquires(torture_ww_mutex_2) locks[2].lock = &torture_ww_mutex_2; list_add(&locks[2].link, &list); - ww_acquire_init(&ctx, &torture_ww_class); + ww_acquire_init(ctx, &torture_ww_class); list_for_each_entry(ll, &list, link) { int err; - err = ww_mutex_lock(ll->lock, &ctx); + err = ww_mutex_lock(ll->lock, ctx); if (!err) continue; @@ -419,26 +431,29 @@ __acquires(torture_ww_mutex_2) if (err != -EDEADLK) return err; - ww_mutex_lock_slow(ll->lock, &ctx); + ww_mutex_lock_slow(ll->lock, ctx); list_move(&ll->link, &list); } - ww_acquire_fini(&ctx); return 0; } -static void torture_ww_mutex_unlock(int tid __maybe_unused) +static void torture_ww_mutex_unlock(int tid) __releases(torture_ww_mutex_0) __releases(torture_ww_mutex_1) __releases(torture_ww_mutex_2) { + struct ww_acquire_ctx *ctx = &ww_acquire_ctxs[tid]; + ww_mutex_unlock(&torture_ww_mutex_0); ww_mutex_unlock(&torture_ww_mutex_1); ww_mutex_unlock(&torture_ww_mutex_2); + ww_acquire_fini(ctx); } static struct lock_torture_ops ww_mutex_lock_ops = { .init = torture_ww_mutex_init, + .exit = torture_ww_mutex_exit, .writelock = torture_ww_mutex_lock, .write_delay = torture_mutex_delay, .task_boost = torture_boost_dummy, @@ -924,16 +939,16 @@ static int __init lock_torture_init(void) goto unwind; } - if (cxt.cur_ops->init) { - cxt.cur_ops->init(); - cxt.init_called = true; - } - if (nwriters_stress >= 0) cxt.nrealwriters_stress = nwriters_stress; else cxt.nrealwriters_stress = 2 * num_online_cpus(); + if (cxt.cur_ops->init) { + cxt.cur_ops->init(); + cxt.init_called = true; + } + #ifdef CONFIG_DEBUG_MUTEXES if (str_has_prefix(torture_type, "mutex")) cxt.debug_lock = true; -- cgit v1.2.3