[PATCH] pi-futex: rt mutex core

Core functions for the rt-mutex subsystem.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 93 insertions, 0 deletions

diff --git a/kernel/rtmutex_common.h b/kernel/rtmutex_common.h
new file mode 100644
index 000000000000..50eed60eb085
--- /dev/null
+++ b/kernel/rtmutex_common.h
@@ -0,0 +1,93 @@
+/*
+ * RT Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains the private data structure and API definitions.
+ */
+
+#ifndef __KERNEL_RTMUTEX_COMMON_H
+#define __KERNEL_RTMUTEX_COMMON_H
+
+#include <linux/rtmutex.h>
+
+/*
+ * This is the control structure for tasks blocked on a rt_mutex,
+ * which is allocated on the kernel stack on of the blocked task.
+ *
+ * @list_entry:         pi node to enqueue into the mutex waiters list
+ * @pi_list_entry:      pi node to enqueue into the mutex owner waiters list
+ * @task:               task reference to the blocked task
+ */
+struct rt_mutex_waiter {
+        struct plist_node       list_entry;
+        struct plist_node       pi_list_entry;
+        struct task_struct      *task;
+        struct rt_mutex         *lock;
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+        unsigned long           ip;
+        pid_t                   deadlock_task_pid;
+        struct rt_mutex         *deadlock_lock;
+#endif
+};
+
+/*
+ * Various helpers to access the waiters-plist:
+ */
+static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
+{
+        return !plist_head_empty(&lock->wait_list);
+}
+
+static inline struct rt_mutex_waiter *
+rt_mutex_top_waiter(struct rt_mutex *lock)
+{
+        struct rt_mutex_waiter *w;
+
+        w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter,
+                               list_entry);
+        BUG_ON(w->lock != lock);
+
+        return w;
+}
+
+static inline int task_has_pi_waiters(struct task_struct *p)
+{
+        return !plist_head_empty(&p->pi_waiters);
+}
+
+static inline struct rt_mutex_waiter *
+task_top_pi_waiter(struct task_struct *p)
+{
+        return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter,
+                                  pi_list_entry);
+}
+
+/*
+ * lock->owner state tracking:
+ */
+#define RT_MUTEX_OWNER_PENDING  1UL
+#define RT_MUTEX_HAS_WAITERS    2UL
+#define RT_MUTEX_OWNER_MASKALL  3UL
+
+static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
+{
+        return (struct task_struct *)
+                ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
+}
+
+static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock)
+{
+        return (struct task_struct *)
+                ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
+}
+
+static inline unsigned long rt_mutex_owner_pending(struct rt_mutex *lock)
+{
+        return (unsigned long)lock->owner & RT_MUTEX_OWNER_PENDING;
+}
+
+#endif