linux-kernel - [tip: locking/core] locking/ww_mutex: Remove DEFINE_WW

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Date:   Fri, 19 Mar 2021 12:54:17 -0000
From:   "tip-bot2 for Waiman Long" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Waiman Long <longman@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: locking/core] locking/ww_mutex: Remove DEFINE_WW_MUTEX() macro

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     5261ced47f8e89173c3b015f6152a05f11a418c3
Gitweb:        https://git.kernel.org/tip/5261ced47f8e89173c3b015f6152a05f11a418c3
Author:        Waiman Long <longman@...hat.com>
AuthorDate:    Thu, 18 Mar 2021 13:28:12 -04:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 19 Mar 2021 12:13:10 +01:00

locking/ww_mutex: Remove DEFINE_WW_MUTEX() macro

The current DEFINE_WW_MUTEX() macro fails to properly set up the lockdep
key of the ww_mutexes causing potential circular locking dependency
splat. Though it is possible to add more macro magic to make it work,
but the result is rather ugly.

Since locktorture was the only user of DEFINE_WW_MUTEX() and the
previous commit has just removed its use. It is easier to just remove
the macro to force future users of ww_mutexes to use ww_mutex_init()
for initialization.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20210318172814.4400-4-longman@redhat.com
---
 include/linux/ww_mutex.h | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 6ecf2a0..b77f39f 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -48,39 +48,26 @@ struct ww_acquire_ctx {
 #endif
 };
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __WW_CLASS_MUTEX_INITIALIZER(lockname, class) \
-		, .ww_class = class
-#else
-# define __WW_CLASS_MUTEX_INITIALIZER(lockname, class)
-#endif
-
 #define __WW_CLASS_INITIALIZER(ww_class, _is_wait_die)	    \
 		{ .stamp = ATOMIC_LONG_INIT(0) \
 		, .acquire_name = #ww_class "_acquire" \
 		, .mutex_name = #ww_class "_mutex" \
 		, .is_wait_die = _is_wait_die }
 
-#define __WW_MUTEX_INITIALIZER(lockname, class) \
-		{ .base =  __MUTEX_INITIALIZER(lockname.base) \
-		__WW_CLASS_MUTEX_INITIALIZER(lockname, class) }
-
 #define DEFINE_WD_CLASS(classname) \
 	struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 1)
 
 #define DEFINE_WW_CLASS(classname) \
 	struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 0)
 
-#define DEFINE_WW_MUTEX(mutexname, ww_class) \
-	struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class)
-
 /**
  * ww_mutex_init - initialize the w/w mutex
  * @lock: the mutex to be initialized
  * @ww_class: the w/w class the mutex should belong to
  *
  * Initialize the w/w mutex to unlocked state and associate it with the given
- * class.
+ * class. Static define macro for w/w mutex is not provided and this function
+ * is the only way to properly initialize the w/w mutex.
  *
  * It is not allowed to initialize an already locked mutex.
  */