The patch titled
sysfs: implement sysfs_dirent active reference and immediate disconnect
has been added to the -mm tree. Its filename is
sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: sysfs: implement sysfs_dirent active reference and immediate disconnect
From: Tejun Heo <htejun@xxxxxxxxx>
Opening a sysfs node references its associated kobject, so userland can
arbitrarily prolong lifetime of a kobject which complicates lifetime rules in
drivers. This patch implements active reference and makes the association
between kobject and sysfs immediately breakable.
Now each sysfs_dirent has two reference counts - s_count and s_active.
s_count is a regular reference count which guarantees that the containing
sysfs_dirent is accessible. As long as s_count reference is held, all sysfs
internal fields in sysfs_dirent are accessible including s_parent and s_name.
The newly added s_active is active reference count. This is acquired by
invoking sysfs_get_active() and it's the caller's responsibility to ensure
sysfs_dirent itself is accessible (should be holding s_count one way or the
other). Dereferencing sysfs_dirent to access objects out of sysfs proper
requires active reference. This includes access to the associated kobjects,
attributes and ops.
The active references can be drained and denied by calling sysfs_deactivate().
All sysfs_dirents must be deactivated after deletion but before the default
reference is dropped. This enables immediate disconnect of sysfs nodes. Once
a sysfs_dirent is deleted, it won't access any entity external to sysfs
proper.
Because attr/bin_attr ops access both the node itself and its parent for
kobject, they need to hold active references to both.
sysfs_get/put_active_two() helpers are provided to help grabbing both
references. Parent's is acquired first and released last.
Unlike other operations, mmapped area lingers on after mmap() is finished and
the module implement implementing it and kobj need to stay referenced till all
the mapped pages are gone. This is accomplished by holding one set of active
references to the bin_attr and its parent if there have been any mmap during
lifetime of an openfile. The references are dropped when the openfile is
released.
This change makes sysfs lifetime rules independent from both kobject's and
module's. It not only fixes several race conditions caused by sysfs not
holding onto the proper module when referencing kobject, but also helps fixing
and simplifying lifetime management in driver model and drivers by taking
sysfs out of the equation.
Please read the following message for more info.
http://article.gmane.org/gmane.linux.kernel/510293
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Cc: Dipankar Sarma <dipankar@xxxxxxxxxx>
Cc: Maneesh Soni <maneesh@xxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/sysfs/bin.c | 95 +++++++++++++++++++++-----------
fs/sysfs/dir.c | 18 +++++-
fs/sysfs/file.c | 132 ++++++++++++++++++++++++++-------------------
fs/sysfs/inode.c | 8 ++
fs/sysfs/sysfs.h | 107 +++++++++++++++++++++++++++++-------
5 files changed, 246 insertions(+), 114 deletions(-)
diff -puN fs/sysfs/bin.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect fs/sysfs/bin.c
--- a/fs/sysfs/bin.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect
+++ a/fs/sysfs/bin.c
@@ -23,6 +23,7 @@
struct bin_buffer {
struct mutex mutex;
void *buffer;
+ int mmapped;
};
static int
@@ -30,12 +31,20 @@ fill_read(struct dentry *dentry, char *b
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
- struct kobject * kobj = to_kobj(dentry->d_parent);
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+ int rc;
+
+ /* need attr_sd for attr, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ rc = -EIO;
+ if (attr->read)
+ rc = attr->read(kobj, buffer, off, count);
- if (!attr->read)
- return -EIO;
+ sysfs_put_active_two(attr_sd);
- return attr->read(kobj, buffer, off, count);
+ return rc;
}
static ssize_t
@@ -79,12 +88,20 @@ flush_write(struct dentry *dentry, char
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
- struct kobject *kobj = to_kobj(dentry->d_parent);
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+ int rc;
+
+ /* need attr_sd for attr, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ rc = -EIO;
+ if (attr->write)
+ rc = attr->write(kobj, buffer, offset, count);
- if (!attr->write)
- return -EIO;
+ sysfs_put_active_two(attr_sd);
- return attr->write(kobj, buffer, offset, count);
+ return rc;
}
static ssize_t write(struct file *file, const char __user *userbuf,
@@ -124,14 +141,24 @@ static int mmap(struct file *file, struc
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
- struct kobject *kobj = to_kobj(file->f_path.dentry->d_parent);
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
int rc;
- if (!attr->mmap)
- return -EINVAL;
-
mutex_lock(&bb->mutex);
- rc = attr->mmap(kobj, attr, vma);
+
+ /* need attr_sd for attr, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ rc = -EINVAL;
+ if (attr->mmap)
+ rc = attr->mmap(kobj, attr, vma);
+
+ if (rc == 0 && !bb->mmapped)
+ bb->mmapped = 1;
+ else
+ sysfs_put_active_two(attr_sd);
+
mutex_unlock(&bb->mutex);
return rc;
@@ -139,58 +166,60 @@ static int mmap(struct file *file, struc
static int open(struct inode * inode, struct file * file)
{
- struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct bin_buffer *bb = NULL;
- int error = -EINVAL;
+ int error;
- if (!kobj || !attr)
- goto Done;
+ /* need attr_sd for attr */
+ if (!sysfs_get_active(attr_sd))
+ return -ENODEV;
- /* Grab the module reference for this attribute if we have one */
+ /* Grab the module reference for this attribute */
error = -ENODEV;
- if (!try_module_get(attr->attr.owner))
- goto Done;
+ if (!try_module_get(attr->attr.owner))
+ goto err_sput;
error = -EACCES;
if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
- goto Error;
+ goto err_mput;
if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
- goto Error;
+ goto err_mput;
error = -ENOMEM;
bb = kzalloc(sizeof(*bb), GFP_KERNEL);
if (!bb)
- goto Error;
+ goto err_mput;
bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!bb->buffer)
- goto Error;
+ goto err_mput;
mutex_init(&bb->mutex);
file->private_data = bb;
- error = 0;
- goto Done;
+ /* open succeeded, put active reference and pin attr_sd */
+ sysfs_put_active(attr_sd);
+ sysfs_get(attr_sd);
+ return 0;
- Error:
- kfree(bb);
+ err_mput:
module_put(attr->attr.owner);
- Done:
- if (error)
- kobject_put(kobj);
+ err_sput:
+ sysfs_put_active(attr_sd);
+ kfree(bb);
return error;
}
static int release(struct inode * inode, struct file * file)
{
- struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct bin_buffer *bb = file->private_data;
- kobject_put(kobj);
+ if (bb->mmapped)
+ sysfs_put_active_two(attr_sd);
+ sysfs_put(attr_sd);
module_put(attr->attr.owner);
kfree(bb->buffer);
kfree(bb);
diff -puN fs/sysfs/dir.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect fs/sysfs/dir.c
--- a/fs/sysfs/dir.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect
+++ a/fs/sysfs/dir.c
@@ -22,6 +22,9 @@ void release_sysfs_dirent(struct sysfs_d
repeat:
parent_sd = sd->s_parent;
+ /* s_active must have been write locked by sysfs_deactivate(), unlock */
+ up_write(&sd->s_active);
+
if (sd->s_type & SYSFS_KOBJ_LINK)
sysfs_put(sd->s_elem.symlink.target_sd);
if (sd->s_type & SYSFS_COPY_NAME)
@@ -69,6 +72,7 @@ struct sysfs_dirent *sysfs_new_dirent(co
atomic_set(&sd->s_count, 1);
atomic_set(&sd->s_event, 1);
+ init_rwsem(&sd->s_active);
INIT_LIST_HEAD(&sd->s_children);
INIT_LIST_HEAD(&sd->s_sibling);
@@ -316,7 +320,6 @@ static void remove_dir(struct dentry * d
d_delete(d);
sd = d->d_fsdata;
list_del_init(&sd->s_sibling);
- sysfs_put(sd);
if (d->d_inode)
simple_rmdir(parent->d_inode,d);
@@ -325,6 +328,9 @@ static void remove_dir(struct dentry * d
mutex_unlock(&parent->d_inode->i_mutex);
dput(parent);
+
+ sysfs_deactivate(sd);
+ sysfs_put(sd);
}
void sysfs_remove_subdir(struct dentry * d)
@@ -335,6 +341,7 @@ void sysfs_remove_subdir(struct dentry *
static void __sysfs_remove_dir(struct dentry *dentry)
{
+ LIST_HEAD(removed);
struct sysfs_dirent * parent_sd;
struct sysfs_dirent * sd, * tmp;
@@ -348,12 +355,17 @@ static void __sysfs_remove_dir(struct de
list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
if (!sd->s_type || !(sd->s_type & SYSFS_NOT_PINNED))
continue;
- list_del_init(&sd->s_sibling);
+ list_move(&sd->s_sibling, &removed);
sysfs_drop_dentry(sd, dentry);
- sysfs_put(sd);
}
mutex_unlock(&dentry->d_inode->i_mutex);
+ list_for_each_entry_safe(sd, tmp, &removed, s_sibling) {
+ list_del_init(&sd->s_sibling);
+ sysfs_deactivate(sd);
+ sysfs_put(sd);
+ }
+
remove_dir(dentry);
/**
* Drop reference from dget() on entrance.
diff -puN fs/sysfs/file.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect fs/sysfs/file.c
--- a/fs/sysfs/file.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect
+++ a/fs/sysfs/file.c
@@ -88,8 +88,8 @@ remove_from_collection(struct sysfs_buff
*/
static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
{
- struct sysfs_dirent * sd = dentry->d_fsdata;
- struct kobject * kobj = to_kobj(dentry->d_parent);
+ struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
struct sysfs_ops * ops = buffer->ops;
int ret = 0;
ssize_t count;
@@ -99,8 +99,15 @@ static int fill_read_buffer(struct dentr
if (!buffer->page)
return -ENOMEM;
- buffer->event = atomic_read(&sd->s_event);
- count = ops->show(kobj, sd->s_elem.attr.attr, buffer->page);
+ /* need attr_sd for attr and ops, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ buffer->event = atomic_read(&attr_sd->s_event);
+ count = ops->show(kobj, attr_sd->s_elem.attr.attr, buffer->page);
+
+ sysfs_put_active_two(attr_sd);
+
BUG_ON(count > (ssize_t)PAGE_SIZE);
if (count >= 0) {
buffer->needs_read_fill = 0;
@@ -225,14 +232,23 @@ fill_write_buffer(struct sysfs_buffer *
* passing the buffer that we acquired in fill_write_buffer().
*/
-static int
+static int
flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
- struct kobject * kobj = to_kobj(dentry->d_parent);
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
struct sysfs_ops * ops = buffer->ops;
+ int rc;
- return ops->store(kobj, attr_sd->s_elem.attr.attr, buffer->page, count);
+ /* need attr_sd for attr and ops, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ rc = ops->store(kobj, attr_sd->s_elem.attr.attr, buffer->page, count);
+
+ sysfs_put_active_two(attr_sd);
+
+ return rc;
}
@@ -276,22 +292,22 @@ out:
static int sysfs_open_file(struct inode *inode, struct file *file)
{
- struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct attribute *attr = attr_sd->s_elem.attr.attr;
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
struct sysfs_buffer_collection *set;
struct sysfs_buffer * buffer;
struct sysfs_ops * ops = NULL;
- int error = 0;
-
- if (!kobj || !attr)
- goto Einval;
+ int error;
- /* Grab the module reference for this attribute if we have one */
- if (!try_module_get(attr->owner)) {
- error = -ENODEV;
- goto Done;
- }
+ /* need attr_sd for attr and ops, its parent for kobj */
+ if (!sysfs_get_active_two(attr_sd))
+ return -ENODEV;
+
+ /* Grab the module reference for this attribute */
+ error = -ENODEV;
+ if (!try_module_get(attr->owner))
+ goto err_sput;
/* if the kobject has no ktype, then we assume that it is a subsystem
* itself, and use ops for it.
@@ -306,30 +322,30 @@ static int sysfs_open_file(struct inode
/* No sysfs operations, either from having no subsystem,
* or the subsystem have no operations.
*/
+ error = -EACCES;
if (!ops)
- goto Eaccess;
+ goto err_mput;
/* make sure we have a collection to add our buffers to */
mutex_lock(&inode->i_mutex);
if (!(set = inode->i_private)) {
- if (!(set = inode->i_private = kmalloc(sizeof(struct sysfs_buffer_collection), GFP_KERNEL))) {
- error = -ENOMEM;
- goto Done;
- } else {
+ error = -ENOMEM;
+ if (!(set = inode->i_private = kmalloc(sizeof(struct sysfs_buffer_collection), GFP_KERNEL)))
+ goto err_mput;
+ else
INIT_LIST_HEAD(&set->associates);
- }
}
mutex_unlock(&inode->i_mutex);
+ error = -EACCES;
+
/* File needs write support.
* The inode's perms must say it's ok,
* and we must have a store method.
*/
if (file->f_mode & FMODE_WRITE) {
-
if (!(inode->i_mode & S_IWUGO) || !ops->store)
- goto Eaccess;
-
+ goto err_mput;
}
/* File needs read support.
@@ -338,46 +354,45 @@ static int sysfs_open_file(struct inode
*/
if (file->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO) || !ops->show)
- goto Eaccess;
+ goto err_mput;
}
/* No error? Great, allocate a buffer for the file, and store it
* it in file->private_data for easy access.
*/
+ error = -ENOMEM;
buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
- if (buffer) {
- INIT_LIST_HEAD(&buffer->associates);
- init_MUTEX(&buffer->sem);
- buffer->needs_read_fill = 1;
- buffer->ops = ops;
- add_to_collection(buffer, inode);
- file->private_data = buffer;
- } else
- error = -ENOMEM;
- goto Done;
+ if (!buffer)
+ goto err_mput;
- Einval:
- error = -EINVAL;
- goto Done;
- Eaccess:
- error = -EACCES;
+ INIT_LIST_HEAD(&buffer->associates);
+ init_MUTEX(&buffer->sem);
+ buffer->needs_read_fill = 1;
+ buffer->ops = ops;
+ add_to_collection(buffer, inode);
+ file->private_data = buffer;
+
+ /* open succeeded, put active references and pin attr_sd */
+ sysfs_put_active_two(attr_sd);
+ sysfs_get(attr_sd);
+ return 0;
+
+ err_mput:
module_put(attr->owner);
- Done:
- if (error)
- kobject_put(kobj);
+ err_sput:
+ sysfs_put_active_two(attr_sd);
return error;
}
static int sysfs_release(struct inode * inode, struct file * filp)
{
- struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
struct attribute *attr = attr_sd->s_elem.attr.attr;
struct sysfs_buffer * buffer = filp->private_data;
if (buffer)
remove_from_collection(buffer, inode);
- kobject_put(kobj);
+ sysfs_put(attr_sd);
/* After this point, attr should not be accessed. */
module_put(attr->owner);
@@ -406,18 +421,25 @@ static int sysfs_release(struct inode *
static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
{
struct sysfs_buffer * buffer = filp->private_data;
- struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
- struct sysfs_dirent * sd = filp->f_path.dentry->d_fsdata;
- int res = 0;
+ struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+ struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+
+ /* need parent for the kobj, grab both */
+ if (!sysfs_get_active_two(attr_sd))
+ goto trigger;
poll_wait(filp, &kobj->poll, wait);
- if (buffer->event != atomic_read(&sd->s_event)) {
- res = POLLERR|POLLPRI;
- buffer->needs_read_fill = 1;
- }
+ sysfs_put_active_two(attr_sd);
- return res;
+ if (buffer->event != atomic_read(&attr_sd->s_event))
+ goto trigger;
+
+ return 0;
+
+ trigger:
+ buffer->needs_read_fill = 1;
+ return POLLERR|POLLPRI;
}
diff -puN fs/sysfs/inode.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect fs/sysfs/inode.c
--- a/fs/sysfs/inode.c~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect
+++ a/fs/sysfs/inode.c
@@ -260,12 +260,16 @@ int sysfs_hash_and_remove(struct dentry
if (!strcmp(sd->s_name, name)) {
list_del_init(&sd->s_sibling);
sysfs_drop_dentry(sd, dir);
- sysfs_put(sd);
found = 1;
break;
}
}
mutex_unlock(&dir->d_inode->i_mutex);
- return found ? 0 : -ENOENT;
+ if (!found)
+ return -ENOENT;
+
+ sysfs_deactivate(sd);
+ sysfs_put(sd);
+ return 0;
}
diff -puN fs/sysfs/sysfs.h~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect fs/sysfs/sysfs.h
--- a/fs/sysfs/sysfs.h~sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect
+++ a/fs/sysfs/sysfs.h
@@ -14,8 +14,14 @@ struct sysfs_elem_bin_attr {
struct bin_attribute * bin_attr;
};
+/*
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible. Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
struct sysfs_dirent {
atomic_t s_count;
+ struct rw_semaphore s_active;
struct sysfs_dirent * s_parent;
struct list_head s_sibling;
struct list_head s_children;
@@ -85,43 +91,102 @@ struct sysfs_buffer_collection {
struct list_head associates;
};
-static inline struct kobject * to_kobj(struct dentry * dentry)
+static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
{
- struct sysfs_dirent * sd = dentry->d_fsdata;
- return sd->s_elem.dir.kobj;
+ if (sd) {
+ WARN_ON(!atomic_read(&sd->s_count));
+ atomic_inc(&sd->s_count);
+ }
+ return sd;
}
-static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
+static inline void sysfs_put(struct sysfs_dirent * sd)
{
- struct kobject * kobj = NULL;
-
- spin_lock(&dcache_lock);
- if (!d_unhashed(dentry)) {
- struct sysfs_dirent * sd = dentry->d_fsdata;
-
- if (sd->s_type & SYSFS_KOBJ_LINK)
- sd = sd->s_elem.symlink.target_sd;
+ if (atomic_dec_and_test(&sd->s_count))
+ release_sysfs_dirent(sd);
+}
- kobj = kobject_get(sd->s_elem.dir.kobj);
+/**
+ * sysfs_get_active - get an active reference to sysfs_dirent
+ * @sd: sysfs_dirent to get an active reference to
+ *
+ * Get an active reference of @sd. This function is noop if @sd
+ * is NULL.
+ *
+ * RETURNS:
+ * Pointer to @sd on success, NULL on failure.
+ */
+static inline struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+ if (sd) {
+ if (unlikely(!down_read_trylock(&sd->s_active)))
+ sd = NULL;
}
- spin_unlock(&dcache_lock);
+ return sd;
+}
- return kobj;
+/**
+ * sysfs_put_active - put an active reference to sysfs_dirent
+ * @sd: sysfs_dirent to put an active reference to
+ *
+ * Put an active reference to @sd. This function is noop if @sd
+ * is NULL.
+ */
+static inline void sysfs_put_active(struct sysfs_dirent *sd)
+{
+ if (sd)
+ up_read(&sd->s_active);
}
-static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
+/**
+ * sysfs_get_active_two - get active references to sysfs_dirent and parent
+ * @sd: sysfs_dirent of interest
+ *
+ * Get active reference to @sd and its parent. Parent's active
+ * reference is grabbed first. This function is noop if @sd is
+ * NULL.
+ *
+ * RETURNS:
+ * Pointer to @sd on success, NULL on failure.
+ */
+static inline struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
{
if (sd) {
- WARN_ON(!atomic_read(&sd->s_count));
- atomic_inc(&sd->s_count);
+ if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
+ return NULL;
+ if (unlikely(!sysfs_get_active(sd))) {
+ sysfs_put_active(sd->s_parent);
+ return NULL;
+ }
}
return sd;
}
-static inline void sysfs_put(struct sysfs_dirent * sd)
+/**
+ * sysfs_put_active_two - put active references to sysfs_dirent and parent
+ * @sd: sysfs_dirent of interest
+ *
+ * Put active references to @sd and its parent. This function is
+ * noop if @sd is NULL.
+ */
+static inline void sysfs_put_active_two(struct sysfs_dirent *sd)
{
- if (atomic_dec_and_test(&sd->s_count))
- release_sysfs_dirent(sd);
+ if (sd) {
+ sysfs_put_active(sd);
+ sysfs_put_active(sd->s_parent);
+ }
+}
+
+/**
+ * sysfs_deactivate - deactivate sysfs_dirent
+ * @sd: sysfs_dirent to deactivate
+ *
+ * Deny new active references and drain existing ones. s_active
+ * will be unlocked when the sysfs_dirent is released.
+ */
+static inline void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+ down_write(&sd->s_active);
}
static inline int sysfs_is_shadowed_inode(struct inode *inode)
_
Patches currently in -mm which might be from htejun@xxxxxxxxx are
origin.patch
revert-gregkh-driver-sysfs-crash-debugging.patch
sysfs-fix-i_ino-handling-in-sysfs.patch
sysfs-fix-error-handling-in-binattr-write.patch
sysfs-move-release_sysfs_dirent-to-dirc.patch
sysfs-flatten-cleanup-paths-in-sysfs_add_link-and-create_dir.patch
sysfs-consolidate-sysfs_dirent-creation-functions.patch
sysfs-add-sysfs_dirent-s_parent.patch
sysfs-add-sysfs_dirent-s_name.patch
sysfs-make-sysfs_dirent-s_element-a-union.patch
sysfs-implement-kobj_sysfs_assoc_lock.patch
sysfs-reimplement-symlink-using-sysfs_dirent-tree.patch
sysfs-implement-bin_buffer.patch
sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect.patch
sysfs-kill-attribute-file-orphaning.patch
sysfs-kill-unnecessary-attribute-owner.patch
sysfs-kill-unnecessary-attribute-owner-fix.patch
git-libata-all.patch
sata_nv-add-back-some-verbosity-into-adma-error_handler.patch
optional-led-trigger-for-libata.patch
drivers-ata-pata_cmd640c-fix-build-with-config_pm=n.patch
git-scsi-misc.patch
introduce-config_has_dma.patch
-
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