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authorJohn Stultz <john.stultz@linaro.org>2013-09-26 12:05:54 -0700
committerJohn Stultz <john.stultz@linaro.org>2013-09-26 12:05:54 -0700
commit17deb9c2db01c7813611291d251d8c7dbdfd3c9d (patch)
tree6e023c0be7c64de84dd51a671eb09c5c82b56615 /include/linux/lockref.h
parentf4e6e1ea19737077d958f2bc6c196eb579d97544 (diff)
parent389e067032fbb96e439abafae848dd447e4cafb4 (diff)
Merge remote-tracking branch 'tip/timers/core' into fordlezcano/3.13/sched-clock64-conversion
Update to tip/timers/core and resolve minor conflict. Conflicts: drivers/clocksource/samsung_pwm_timer.c Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'include/linux/lockref.h')
-rw-r--r--include/linux/lockref.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/include/linux/lockref.h b/include/linux/lockref.h
new file mode 100644
index 000000000000..f279ed9a9163
--- /dev/null
+++ b/include/linux/lockref.h
@@ -0,0 +1,39 @@
+#ifndef __LINUX_LOCKREF_H
+#define __LINUX_LOCKREF_H
+
+/*
+ * Locked reference counts.
+ *
+ * These are different from just plain atomic refcounts in that they
+ * are atomic with respect to the spinlock that goes with them. In
+ * particular, there can be implementations that don't actually get
+ * the spinlock for the common decrement/increment operations, but they
+ * still have to check that the operation is done semantically as if
+ * the spinlock had been taken (using a cmpxchg operation that covers
+ * both the lock and the count word, or using memory transactions, for
+ * example).
+ */
+
+#include <linux/spinlock.h>
+
+struct lockref {
+ union {
+#ifdef CONFIG_CMPXCHG_LOCKREF
+ aligned_u64 lock_count;
+#endif
+ struct {
+ spinlock_t lock;
+ unsigned int count;
+ };
+ };
+};
+
+extern void lockref_get(struct lockref *);
+extern int lockref_get_not_zero(struct lockref *);
+extern int lockref_get_or_lock(struct lockref *);
+extern int lockref_put_or_lock(struct lockref *);
+
+extern void lockref_mark_dead(struct lockref *);
+extern int lockref_get_not_dead(struct lockref *);
+
+#endif /* __LINUX_LOCKREF_H */