locking: WW mutex cleanup
Make the WW mutex code more readable by adding comments, splitting up
functions and pointing out that we're actually using the Wait-Die
algorithm.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Co-authored-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 39fda19..f82fce2 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -6,7 +6,7 @@
*
* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*
- * Wound/wait implementation:
+ * Wait/Die implementation:
* Copyright (C) 2013 Canonical Ltd.
*
* This file contains the main data structure and API definitions.
@@ -28,9 +28,9 @@
struct ww_acquire_ctx {
struct task_struct *task;
unsigned long stamp;
- unsigned acquired;
+ unsigned int acquired;
#ifdef CONFIG_DEBUG_MUTEXES
- unsigned done_acquire;
+ unsigned int done_acquire;
struct ww_class *ww_class;
struct ww_mutex *contending_lock;
#endif
@@ -38,8 +38,8 @@
struct lockdep_map dep_map;
#endif
#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
- unsigned deadlock_inject_interval;
- unsigned deadlock_inject_countdown;
+ unsigned int deadlock_inject_interval;
+ unsigned int deadlock_inject_countdown;
#endif
};
@@ -102,7 +102,7 @@
*
* Context-based w/w mutex acquiring can be done in any order whatsoever within
* a given lock class. Deadlocks will be detected and handled with the
- * wait/wound logic.
+ * wait/die logic.
*
* Mixing of context-based w/w mutex acquiring and single w/w mutex locking can
* result in undetected deadlocks and is so forbidden. Mixing different contexts
@@ -195,13 +195,13 @@
* Lock the w/w mutex exclusively for this task.
*
* Deadlocks within a given w/w class of locks are detected and handled with the
- * wait/wound algorithm. If the lock isn't immediately avaiable this function
+ * wait/die algorithm. If the lock isn't immediately available this function
* will either sleep until it is (wait case). Or it selects the current context
- * for backing off by returning -EDEADLK (wound case). Trying to acquire the
+ * for backing off by returning -EDEADLK (die case). Trying to acquire the
* same lock with the same context twice is also detected and signalled by
* returning -EALREADY. Returns 0 if the mutex was successfully acquired.
*
- * In the wound case the caller must release all currently held w/w mutexes for
+ * In the die case the caller must release all currently held w/w mutexes for
* the given context and then wait for this contending lock to be available by
* calling ww_mutex_lock_slow. Alternatively callers can opt to not acquire this
* lock and proceed with trying to acquire further w/w mutexes (e.g. when
@@ -226,14 +226,14 @@
* Lock the w/w mutex exclusively for this task.
*
* Deadlocks within a given w/w class of locks are detected and handled with the
- * wait/wound algorithm. If the lock isn't immediately avaiable this function
+ * wait/die algorithm. If the lock isn't immediately available this function
* will either sleep until it is (wait case). Or it selects the current context
- * for backing off by returning -EDEADLK (wound case). Trying to acquire the
+ * for backing off by returning -EDEADLK (die case). Trying to acquire the
* same lock with the same context twice is also detected and signalled by
* returning -EALREADY. Returns 0 if the mutex was successfully acquired. If a
* signal arrives while waiting for the lock then this function returns -EINTR.
*
- * In the wound case the caller must release all currently held w/w mutexes for
+ * In the die case the caller must release all currently held w/w mutexes for
* the given context and then wait for this contending lock to be available by
* calling ww_mutex_lock_slow_interruptible. Alternatively callers can opt to
* not acquire this lock and proceed with trying to acquire further w/w mutexes
@@ -256,7 +256,7 @@
* @lock: the mutex to be acquired
* @ctx: w/w acquire context
*
- * Acquires a w/w mutex with the given context after a wound case. This function
+ * Acquires a w/w mutex with the given context after a die case. This function
* will sleep until the lock becomes available.
*
* The caller must have released all w/w mutexes already acquired with the
@@ -290,7 +290,7 @@
* @lock: the mutex to be acquired
* @ctx: w/w acquire context
*
- * Acquires a w/w mutex with the given context after a wound case. This function
+ * Acquires a w/w mutex with the given context after a die case. This function
* will sleep until the lock becomes available and returns 0 when the lock has
* been acquired. If a signal arrives while waiting for the lock then this
* function returns -EINTR.