linux-kernel - [PATCH] locking/ww_mutex: Fix ww_mutex dummy lockdep map selftest warnings

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Message-ID: <20241127085430.3045-1-thomas.hellstrom@linux.intel.com>
Date: Wed, 27 Nov 2024 09:54:30 +0100
From: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
To: intel-xe@...ts.freedesktop.org
Cc: Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Maarten Lankhorst <maarten@...khorst.se>,
	Christian König <christian.koenig@....com>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] locking/ww_mutex: Fix ww_mutex dummy lockdep map selftest warnings

The below commit introduces a dummy lockdep map, but didn't get
the initialization quite right (it should mimic the initialization
of the real ww_mutex lockdep maps). It also introduced a separate
locking api selftest failure. Fix these.

Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Will Deacon <will@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Maarten Lankhorst <maarten@...khorst.se>
Cc: Christian König <christian.koenig@....com>
Cc: dri-devel@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org
Suggested-by: Boqun Feng <boqun.feng@...il.com>
Reported-by: Boqun Feng <boqun.feng@...il.com>
Closes: https://lore.kernel.org/lkml/Zw19sMtnKdyOVQoh@boqun-archlinux/
Fixes: 823a566221a5 ("locking/ww_mutex: Adjust to lockdep nest_lock requirements")
Signed-off-by: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
---
 include/linux/ww_mutex.h | 4 ++--
 lib/locking-selftest.c   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index a401a2f31a77..45ff6f7a872b 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -156,8 +156,8 @@ static inline void ww_acquire_init(struct ww_acquire_ctx *ctx,
 	debug_check_no_locks_freed((void *)ctx, sizeof(*ctx));
 	lockdep_init_map(&ctx->dep_map, ww_class->acquire_name,
 			 &ww_class->acquire_key, 0);
-	lockdep_init_map(&ctx->first_lock_dep_map, ww_class->mutex_name,
-			 &ww_class->mutex_key, 0);
+	lockdep_init_map_wait(&ctx->first_lock_dep_map, ww_class->mutex_name,
+			      &ww_class->mutex_key, 0, LD_WAIT_SLEEP);
 	mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_);
 	mutex_acquire_nest(&ctx->first_lock_dep_map, 0, 0, &ctx->dep_map, _RET_IP_);
 #endif
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 6e0c019f71b6..ed99344317f5 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -1720,8 +1720,6 @@ static void ww_test_normal(void)
 {
 	int ret;
 
-	WWAI(&t);
-
 	/*
 	 * None of the ww_mutex codepaths should be taken in the 'normal'
 	 * mutex calls. The easiest way to verify this is by using the
@@ -1770,6 +1768,8 @@ static void ww_test_normal(void)
 	ww_mutex_base_unlock(&o.base);
 	WARN_ON(o.ctx != (void *)~0UL);
 
+	WWAI(&t);
+
 	/* nest_lock */
 	o.ctx = (void *)~0UL;
 	ww_mutex_base_lock_nest_lock(&o.base, &t);
-- 
2.47.0