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sysfs: use sysfs_mutex to protect the sysfs_dirent tree

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As kobj sysfs dentries and inodes are gonna be made reclaimable,
i_mutex can't be used to protect sysfs_dirent tree.  Use sysfs_mutex
globally instead.  As the whole tree is protected with sysfs_mutex,
there is no reason to keep sysfs_rename_sem.  Drop it.

While at it, add docbook comments to functions which require
sysfs_mutex locking.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Tejun Heo
2007-06-14 04:27:23 +09:00
committed by Greg Kroah-Hartman
parent 5f9953237f
commit 3007e997de
5 changed files with 117 additions and 81 deletions
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51
fs/sysfs/symlink.c
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@@ -44,20 +44,6 @@ static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length)
}
}
static int sysfs_add_link(struct sysfs_dirent * parent_sd, const char * name,
struct sysfs_dirent * target_sd)
{
struct sysfs_dirent * sd;
sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
if (!sd)
return -ENOMEM;
sd->s_elem.symlink.target_sd = target_sd;
sysfs_attach_dirent(sd, parent_sd, NULL);
return 0;
}
/**
* sysfs_create_link - create symlink between two objects.
* @kobj: object whose directory we're creating the link in.
@@ -68,7 +54,8 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
{
struct sysfs_dirent *parent_sd = NULL;
struct sysfs_dirent *target_sd = NULL;
int error = -EEXIST;
struct sysfs_dirent *sd = NULL;
int error;
BUG_ON(!name);
@@ -78,8 +65,9 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
} else
parent_sd = kobj->sd;
error = -EFAULT;
if (!parent_sd)
return -EFAULT;
goto out_put;
/* target->sd can go away beneath us but is protected with
* sysfs_assoc_lock. Fetch target_sd from it.
@@ -89,17 +77,30 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
target_sd = sysfs_get(target->sd);
spin_unlock(&sysfs_assoc_lock);
error = -ENOENT;
if (!target_sd)
return -ENOENT;
goto out_put;
mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
if (!sysfs_find_dirent(parent_sd, name))
error = sysfs_add_link(parent_sd, name, target_sd);
mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
error = -ENOMEM;
sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
if (!sd)
goto out_put;
sd->s_elem.symlink.target_sd = target_sd;
if (error)
sysfs_put(target_sd);
mutex_lock(&sysfs_mutex);
error = -EEXIST;
if (sysfs_find_dirent(parent_sd, name))
goto out_unlock;
sysfs_attach_dirent(sd, parent_sd, NULL);
mutex_unlock(&sysfs_mutex);
return 0;
out_unlock:
mutex_unlock(&sysfs_mutex);
out_put:
sysfs_put(target_sd);
sysfs_put(sd);
return error;
}
@@ -144,9 +145,9 @@ static int sysfs_getlink(struct dentry *dentry, char * path)
struct sysfs_dirent *target_sd = sd->s_elem.symlink.target_sd;
int error;
down_read(&sysfs_rename_sem);
mutex_lock(&sysfs_mutex);
error = sysfs_get_target_path(parent_sd, target_sd, path);
up_read(&sysfs_rename_sem);
mutex_unlock(&sysfs_mutex);
return error;
}