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authorSean Paul <seanpaul@chromium.org>2017-05-18 09:24:30 -0400
committerSean Paul <seanpaul@chromium.org>2017-05-18 09:24:30 -0400
commit6b7781b42dc9bc9bcd1523b6c24b876cdda0bef3 (patch)
treeee55c67e4ea30b9eb44f301ba0bde2e631a26162 /include/linux/refcount.h
parent52d9d38c183bf0e09601d875ea31bb53c05dd8cf (diff)
parente98c58e55f68f8785aebfab1f8c9a03d8de0afe1 (diff)
downloadlwn-6b7781b42dc9bc9bcd1523b6c24b876cdda0bef3.tar.gz
lwn-6b7781b42dc9bc9bcd1523b6c24b876cdda0bef3.zip
Merge remote-tracking branch 'airlied/drm-next' into drm-misc-next
Picking up drm-next @ 4.12-rc1 in order to apply Michal Hocko's vmalloc patch set Signed-off-by: Sean Paul <seanpaul@chromium.org>
Diffstat (limited to 'include/linux/refcount.h')
-rw-r--r--include/linux/refcount.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/refcount.h b/include/linux/refcount.h
index 0023fee4bbbc..b34aa649d204 100644
--- a/include/linux/refcount.h
+++ b/include/linux/refcount.h
@@ -6,17 +6,36 @@
#include <linux/spinlock.h>
#include <linux/kernel.h>
+/**
+ * refcount_t - variant of atomic_t specialized for reference counts
+ * @refs: atomic_t counter field
+ *
+ * The counter saturates at UINT_MAX and will not move once
+ * there. This avoids wrapping the counter and causing 'spurious'
+ * use-after-free bugs.
+ */
typedef struct refcount_struct {
atomic_t refs;
} refcount_t;
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
+/**
+ * refcount_set - set a refcount's value
+ * @r: the refcount
+ * @n: value to which the refcount will be set
+ */
static inline void refcount_set(refcount_t *r, unsigned int n)
{
atomic_set(&r->refs, n);
}
+/**
+ * refcount_read - get a refcount's value
+ * @r: the refcount
+ *
+ * Return: the refcount's value
+ */
static inline unsigned int refcount_read(const refcount_t *r)
{
return atomic_read(&r->refs);