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Subject[PATCH] plist: add mutex to the blessed lock type for plists
Date
Currently, plist debugging "enforces" that the plist is locked
with either a raw_spinlock or a spinlock. The plist data structure
is useful in other places, where spinlocks are unnecessary.

Extend the plist initializers and debug checks to allow the plist
to be protected by a mutex

Signed-off-by: Dima Zavin <dima@android.com>
---
include/linux/plist.h | 33 +++++++++++++++++++++++++++++++++
lib/plist.c | 6 +++++-
2 files changed, 38 insertions(+), 1 deletions(-)

diff --git a/include/linux/plist.h b/include/linux/plist.h
index c9b9f32..bd670f6 100644
--- a/include/linux/plist.h
+++ b/include/linux/plist.h
@@ -77,6 +77,7 @@

#include <linux/kernel.h>
#include <linux/list.h>
+#include <linux/mutex.h>
#include <linux/spinlock_types.h>

struct plist_head {
@@ -84,6 +85,7 @@ struct plist_head {
#ifdef CONFIG_DEBUG_PI_LIST
raw_spinlock_t *rawlock;
spinlock_t *spinlock;
+ struct mutex *mutex;
#endif
};

@@ -96,9 +98,11 @@ struct plist_node {
#ifdef CONFIG_DEBUG_PI_LIST
# define PLIST_HEAD_LOCK_INIT(_lock) .spinlock = _lock
# define PLIST_HEAD_LOCK_INIT_RAW(_lock) .rawlock = _lock
+# define PLIST_HEAD_LOCK_INIT_MUTEX(_lock) .mutex = _lock
#else
# define PLIST_HEAD_LOCK_INIT(_lock)
# define PLIST_HEAD_LOCK_INIT_RAW(_lock)
+# define PLIST_HEAD_LOCK_INIT_MUTEX(_lock)
#endif

#define _PLIST_HEAD_INIT(head) \
@@ -127,6 +131,17 @@ struct plist_node {
}

/**
+ * PLIST_HEAD_INIT_MUTEX - static struct plist_head initializer
+ * @head: struct plist_head variable name
+ * @_lock: lock to initialize for this list
+ */
+#define PLIST_HEAD_INIT_MUTEX(head, _lock) \
+{ \
+ _PLIST_HEAD_INIT(head), \
+ PLIST_HEAD_LOCK_INIT_MUTEX(&(_lock)) \
+}
+
+/**
* PLIST_NODE_INIT - static struct plist_node initializer
* @node: struct plist_node variable name
* @__prio: initial node priority
@@ -150,6 +165,7 @@ plist_head_init(struct plist_head *head, spinlock_t *lock)
#ifdef CONFIG_DEBUG_PI_LIST
head->spinlock = lock;
head->rawlock = NULL;
+ head->mutex = NULL;
#endif
}

@@ -165,6 +181,23 @@ plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
#ifdef CONFIG_DEBUG_PI_LIST
head->rawlock = lock;
head->spinlock = NULL;
+ head->mutex = NULL;
+#endif
+}
+
+/**
+ * plist_head_init_mutex - dynamic struct plist_head initializer
+ * @head: &struct plist_head pointer
+ * @lock: mutex protecting the list (debugging)
+ */
+static inline void
+plist_head_init_mutex(struct plist_head *head, struct mutex *lock)
+{
+ INIT_LIST_HEAD(&head->node_list);
+#ifdef CONFIG_DEBUG_PI_LIST
+ head->mutex = lock;
+ head->rawlock = NULL;
+ head->spinlock = NULL;
#endif
}

diff --git a/lib/plist.c b/lib/plist.c
index 0ae7e64..f3c2cad 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -23,6 +23,7 @@
* information.
*/

+#include <linux/mutex.h>
#include <linux/plist.h>
#include <linux/spinlock.h>

@@ -56,11 +57,14 @@ static void plist_check_list(struct list_head *top)

static void plist_check_head(struct plist_head *head)
{
- WARN_ON(head != &test_head && !head->rawlock && !head->spinlock);
+ WARN_ON(head != &test_head && !head->rawlock && !head->spinlock &&
+ !head->mutex);
if (head->rawlock)
WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
if (head->spinlock)
WARN_ON_SMP(!spin_is_locked(head->spinlock));
+ if (head->mutex)
+ WARN_ON(!mutex_is_locked(head->mutex));
if (!plist_head_empty(head))
plist_check_list(&plist_first(head)->prio_list);
plist_check_list(&head->node_list);
--
1.7.3.1


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