[PATCH 20/39] sysfs, kernfs: introduce kernfs_notify()

Tejun Heo
2013-11-03T10:00:44Z

Introduce kernfs interface to wake up poll(2) which takes and returns
sysfs_dirents.

sysfs_notify_dirent() is renamed to kernfs_notify() and sysfs_notify()
is updated so that it doesn't directly grab sysfs_mutex but acquires
the target sysfs_dirents using sysfs_get_dirent().
sysfs_notify_dirent() is reimplemented as a dumb inline wrapper around
kernfs_notify().

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
fs/sysfs/file.c | 33 ++++++++++++++++++++++-----------
include/linux/kernfs.h | 3 +++
include/linux/sysfs.h | 9 +++++----
3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 3d50f11..1f99fe3 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -834,7 +834,13 @@ static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}

-void sysfs_notify_dirent(struct sysfs_dirent *sd)
+/**
+ * kernfs_notify - notify a kernfs file
+ * @sd: file to notify
+ *
+ * Notify @sd such that poll(2) on @sd wakes up.
+ */
+void kernfs_notify(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
unsigned long flags;
@@ -851,22 +857,27 @@ void sysfs_notify_dirent(struct sysfs_dirent *sd)

spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
}
-EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
+EXPORT_SYMBOL_GPL(kernfs_notify);

void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
{
- struct sysfs_dirent *sd = k->sd;
-
- mutex_lock(&sysfs_mutex);
+ struct sysfs_dirent *sd = k->sd, *tmp;

if (sd && dir)
- sd = sysfs_find_dirent(sd, dir, NULL);
- if (sd && attr)
- sd = sysfs_find_dirent(sd, attr, NULL);
- if (sd)
- sysfs_notify_dirent(sd);
+ sd = sysfs_get_dirent(sd, dir);
+ else
+ sysfs_get(sd);

- mutex_unlock(&sysfs_mutex);
+ if (sd && attr) {
+ tmp = sysfs_get_dirent(sd, attr);
+ sysfs_put(sd);
+ sd = tmp;
+ }
+
+ if (sd) {
+ kernfs_notify(sd);
+ sysfs_put(sd);
+ }
}
EXPORT_SYMBOL_GPL(sysfs_notify);

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index d93c5ef..53cf787 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -83,6 +83,7 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
const char *new_name, const void *new_ns);
int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
+void kernfs_notify(struct sysfs_dirent *sd);

#else /* CONFIG_SYSFS */

@@ -117,6 +118,8 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
const struct iattr *iattr)
{ return -ENOSYS; }

+static inline void kernfs_notify(struct sysfs_dirent *sd) { }
+
#endif /* CONFIG_SYSFS */

static inline struct sysfs_dirent *
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 2bc735d..0ab2b02 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,7 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
const char *link_name);

void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-void sysfs_notify_dirent(struct sysfs_dirent *sd);
struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
const unsigned char *name,
const void *ns);
@@ -418,9 +417,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
const char *attr)
{
}
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
-{
-}
static inline struct sysfs_dirent *
sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
const void *ns)
@@ -466,4 +462,9 @@ sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
return sysfs_get_dirent_ns(parent_sd, name, NULL);
}

+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+ kernfs_notify(sd);
+}
+
#endif /* _SYSFS_H_ */
--
1.8.3.1