summaryrefslogtreecommitdiffstats
path: root/include/linux/kref.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2012-01-07 12:03:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-07 12:03:30 -0800
commit7affca3537d74365128e477b40c529d6f2fe86c8 (patch)
tree20be92bd240029182fc89c2c4f25401b7715dcae /include/linux/kref.h
parent356b95424cfb456e14a59eaa579422ce014c424b (diff)
parentff4b8a57f0aaa2882d444ca44b2b9b333d22a4df (diff)
Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (73 commits) arm: fix up some samsung merge sysdev conversion problems firmware: Fix an oops on reading fw_priv->fw in sysfs loading file Drivers:hv: Fix a bug in vmbus_driver_unregister() driver core: remove __must_check from device_create_file debugfs: add missing #ifdef HAS_IOMEM arm: time.h: remove device.h #include driver-core: remove sysdev.h usage. clockevents: remove sysdev.h arm: convert sysdev_class to a regular subsystem arm: leds: convert sysdev_class to a regular subsystem kobject: remove kset_find_obj_hinted() m86k: gpio - convert sysdev_class to a regular subsystem mips: txx9_sram - convert sysdev_class to a regular subsystem mips: 7segled - convert sysdev_class to a regular subsystem sh: dma - convert sysdev_class to a regular subsystem sh: intc - convert sysdev_class to a regular subsystem power: suspend - convert sysdev_class to a regular subsystem power: qe_ic - convert sysdev_class to a regular subsystem power: cmm - convert sysdev_class to a regular subsystem s390: time - convert sysdev_class to a regular subsystem ... Fix up conflicts with 'struct sysdev' removal from various platform drivers that got changed: - arch/arm/mach-exynos/cpu.c - arch/arm/mach-exynos/irq-eint.c - arch/arm/mach-s3c64xx/common.c - arch/arm/mach-s3c64xx/cpu.c - arch/arm/mach-s5p64x0/cpu.c - arch/arm/mach-s5pv210/common.c - arch/arm/plat-samsung/include/plat/cpu.h - arch/powerpc/kernel/sysfs.c and fix up cpu_is_hotpluggable() as per Greg in include/linux/cpu.h
Diffstat (limited to 'include/linux/kref.h')
-rw-r--r--include/linux/kref.h77
1 files changed, 71 insertions, 6 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h
index d4a62ab2ee5..abc0120b09b 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -15,16 +15,81 @@
#ifndef _KREF_H_
#define _KREF_H_
-#include <linux/types.h>
+#include <linux/bug.h>
+#include <linux/atomic.h>
struct kref {
atomic_t refcount;
};
-void kref_init(struct kref *kref);
-void kref_get(struct kref *kref);
-int kref_put(struct kref *kref, void (*release) (struct kref *kref));
-int kref_sub(struct kref *kref, unsigned int count,
- void (*release) (struct kref *kref));
+/**
+ * kref_init - initialize object.
+ * @kref: object in question.
+ */
+static inline void kref_init(struct kref *kref)
+{
+ atomic_set(&kref->refcount, 1);
+}
+
+/**
+ * kref_get - increment refcount for object.
+ * @kref: object.
+ */
+static inline void kref_get(struct kref *kref)
+{
+ WARN_ON(!atomic_read(&kref->refcount));
+ atomic_inc(&kref->refcount);
+}
+/**
+ * kref_sub - subtract a number of refcounts for object.
+ * @kref: object.
+ * @count: Number of recounts to subtract.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function. If the caller does pass kfree to this
+ * function, you will be publicly mocked mercilessly by the kref
+ * maintainer, and anyone else who happens to notice it. You have
+ * been warned.
+ *
+ * Subtract @count from the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_sub(struct kref *kref, unsigned int count,
+ void (*release)(struct kref *kref))
+{
+ WARN_ON(release == NULL);
+
+ if (atomic_sub_and_test((int) count, &kref->refcount)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
+
+/**
+ * kref_put - decrement refcount for object.
+ * @kref: object.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function. If the caller does pass kfree to this
+ * function, you will be publicly mocked mercilessly by the kref
+ * maintainer, and anyone else who happens to notice it. You have
+ * been warned.
+ *
+ * Decrement the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+ return kref_sub(kref, 1, release);
+}
#endif /* _KREF_H_ */