sysfs: implement sysfs_dirent active reference and immediate disconnect

[powerpc.git] / fs / sysfs / bin.c

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 5dc47fe..618b8ae 100644 (file)
--- a/fs/sysfs/bin.c
+++ b/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 *buffer, loff_t off, size_t count)
 {
        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;
 
-       if (!attr->read)
-               return -EIO;
+       rc = -EIO;
+       if (attr->read)
+               rc = attr->read(kobj, buffer, off, count);
 
-       return attr->read(kobj, buffer, off, count);
+       sysfs_put_active_two(attr_sd);
+
+       return rc;
 }
 
 static ssize_t
@@ -79,12 +88,20 @@ flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
 {
        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;
 
-       if (!attr->write)
-               return -EIO;
+       rc = -EIO;
+       if (attr->write)
+               rc = attr->write(kobj, buffer, offset, count);
 
-       return attr->write(kobj, buffer, offset, count);
+       sysfs_put_active_two(attr_sd);
+
+       return rc;
 }
 
 static ssize_t write(struct file *file, const char __user *userbuf,
@@ -124,14 +141,24 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
        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, struct vm_area_struct *vma)
 
 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);