Prev: [PATCH 1/3] sysfs: simplify handling for s_active refcount
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From: NeilBrown on 23 Mar 2010 23:30
s_count in sysfs behaves exactly like a kref, so change it to
be one.
This requires adding a KREF_INIT macro to kref.h

Signed-off-by: NeilBrown <neilb(a)suse.de>
---
fs/sysfs/dir.c | 12 +++++++++---
fs/sysfs/mount.c | 2 +-
fs/sysfs/sysfs.h | 15 +++++++--------
include/linux/kref.h | 1 +
4 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 76a2d10..63790ac 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -177,8 +177,14 @@ static void sysfs_free_ino(ino_t ino)
spin_unlock(&sysfs_ino_lock);
}

-void release_sysfs_dirent(struct sysfs_dirent * sd)
+static void no_recurse(struct kref *kref)
{
+}
+void release_sysfs_dirent(struct kref *count)
+{
+ struct sysfs_dirent *sd = container_of(count,
+ struct sysfs_dirent,
+ s_count);
struct sysfs_dirent *parent_sd;

repeat:
@@ -199,7 +205,7 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
kmem_cache_free(sysfs_dir_cachep, sd);

sd = parent_sd;
- if (sd && atomic_dec_and_test(&sd->s_count))
+ if (sd && kref_put(&sd->s_count, no_recurse))
goto repeat;
}

@@ -289,7 +295,7 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
if (sysfs_alloc_ino(&sd->s_ino))
goto err_out2;

- atomic_set(&sd->s_count, 1);
+ kref_init(&sd->s_count);
atomic_set(&sd->s_active, 1);

sd->s_name = name;
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 0cb1088..07bff03 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -33,7 +33,7 @@ static const struct super_operations sysfs_ops = {

struct sysfs_dirent sysfs_root = {
.s_name = "",
- .s_count = ATOMIC_INIT(1),
+ .s_count = KREF_INIT,
.s_flags = SYSFS_DIR,
.s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
.s_ino = 1,
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6a2a60e..f003a88 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -49,7 +49,7 @@ struct sysfs_inode_attrs {
* requires s_active reference.
*/
struct sysfs_dirent {
- atomic_t s_count;
+ struct kref s_count;
atomic_t s_active;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
@@ -140,7 +140,7 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);

-void release_sysfs_dirent(struct sysfs_dirent *sd);
+void release_sysfs_dirent(struct kref *count);

int sysfs_create_subdir(struct kobject *kobj, const char *name,
struct sysfs_dirent **p_sd);
@@ -151,18 +151,17 @@ int sysfs_rename(struct sysfs_dirent *sd,

static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
{
- if (sd) {
- WARN_ON(!atomic_read(&sd->s_count));
- atomic_inc(&sd->s_count);
- }
+ if (sd)
+ kref_get(&sd->s_count);
+
return sd;
}
#define sysfs_get(sd) __sysfs_get(sd)

static inline void __sysfs_put(struct sysfs_dirent *sd)
{
- if (sd && atomic_dec_and_test(&sd->s_count))
- release_sysfs_dirent(sd);
+ if (sd)
+ kref_put(&sd->s_count, release_sysfs_dirent);
}
#define sysfs_put(sd) __sysfs_put(sd)

diff --git a/include/linux/kref.h b/include/linux/kref.h
index 13003ee..b006f74 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -25,4 +25,5 @@ void kref_init(struct kref *kref);
void kref_get(struct kref *kref);
int kref_put(struct kref *kref, void (*release) (struct kref *kref));

+#define KREF_INIT {ATOMIC_INIT(1)}
#endif /* _KREF_H_ */


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Prev: [PATCH 1/3] sysfs: simplify handling for s_active refcount
Next: [PATCH 1/2] sis-agp: Remove SIS 760, handled by amd64-agp