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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/sysfs/file.c | |
download | linux-fsl-qoriq-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'fs/sysfs/file.c')
-rw-r--r-- | fs/sysfs/file.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c new file mode 100644 index 0000000..352f966 --- /dev/null +++ b/fs/sysfs/file.c @@ -0,0 +1,447 @@ +/* + * file.c - operations for regular (text) files. + */ + +#include <linux/module.h> +#include <linux/dnotify.h> +#include <linux/kobject.h> +#include <asm/uaccess.h> +#include <asm/semaphore.h> + +#include "sysfs.h" + +#define to_subsys(k) container_of(k,struct subsystem,kset.kobj) +#define to_sattr(a) container_of(a,struct subsys_attribute,attr) + +/** + * Subsystem file operations. + * These operations allow subsystems to have files that can be + * read/written. + */ +static ssize_t +subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page) +{ + struct subsystem * s = to_subsys(kobj); + struct subsys_attribute * sattr = to_sattr(attr); + ssize_t ret = 0; + + if (sattr->show) + ret = sattr->show(s,page); + return ret; +} + +static ssize_t +subsys_attr_store(struct kobject * kobj, struct attribute * attr, + const char * page, size_t count) +{ + struct subsystem * s = to_subsys(kobj); + struct subsys_attribute * sattr = to_sattr(attr); + ssize_t ret = 0; + + if (sattr->store) + ret = sattr->store(s,page,count); + return ret; +} + +static struct sysfs_ops subsys_sysfs_ops = { + .show = subsys_attr_show, + .store = subsys_attr_store, +}; + + +struct sysfs_buffer { + size_t count; + loff_t pos; + char * page; + struct sysfs_ops * ops; + struct semaphore sem; + int needs_read_fill; +}; + + +/** + * fill_read_buffer - allocate and fill buffer from object. + * @dentry: dentry pointer. + * @buffer: data buffer for file. + * + * Allocate @buffer->page, if it hasn't been already, then call the + * kobject's show() method to fill the buffer with this attribute's + * data. + * This is called only once, on the file's first read. + */ +static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer) +{ + struct attribute * attr = to_attr(dentry); + struct kobject * kobj = to_kobj(dentry->d_parent); + struct sysfs_ops * ops = buffer->ops; + int ret = 0; + ssize_t count; + + if (!buffer->page) + buffer->page = (char *) get_zeroed_page(GFP_KERNEL); + if (!buffer->page) + return -ENOMEM; + + count = ops->show(kobj,attr,buffer->page); + buffer->needs_read_fill = 0; + BUG_ON(count > (ssize_t)PAGE_SIZE); + if (count >= 0) + buffer->count = count; + else + ret = count; + return ret; +} + + +/** + * flush_read_buffer - push buffer to userspace. + * @buffer: data buffer for file. + * @userbuf: user-passed buffer. + * @count: number of bytes requested. + * @ppos: file position. + * + * Copy the buffer we filled in fill_read_buffer() to userspace. + * This is done at the reader's leisure, copying and advancing + * the amount they specify each time. + * This may be called continuously until the buffer is empty. + */ +static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf, + size_t count, loff_t * ppos) +{ + int error; + + if (*ppos > buffer->count) + return 0; + + if (count > (buffer->count - *ppos)) + count = buffer->count - *ppos; + + error = copy_to_user(buf,buffer->page + *ppos,count); + if (!error) + *ppos += count; + return error ? -EFAULT : count; +} + +/** + * sysfs_read_file - read an attribute. + * @file: file pointer. + * @buf: buffer to fill. + * @count: number of bytes to read. + * @ppos: starting offset in file. + * + * Userspace wants to read an attribute file. The attribute descriptor + * is in the file's ->d_fsdata. The target object is in the directory's + * ->d_fsdata. + * + * We call fill_read_buffer() to allocate and fill the buffer from the + * object's show() method exactly once (if the read is happening from + * the beginning of the file). That should fill the entire buffer with + * all the data the object has to offer for that attribute. + * We then call flush_read_buffer() to copy the buffer to userspace + * in the increments specified. + */ + +static ssize_t +sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) +{ + struct sysfs_buffer * buffer = file->private_data; + ssize_t retval = 0; + + down(&buffer->sem); + if (buffer->needs_read_fill) { + if ((retval = fill_read_buffer(file->f_dentry,buffer))) + goto out; + } + pr_debug("%s: count = %d, ppos = %lld, buf = %s\n", + __FUNCTION__,count,*ppos,buffer->page); + retval = flush_read_buffer(buffer,buf,count,ppos); +out: + up(&buffer->sem); + return retval; +} + + +/** + * fill_write_buffer - copy buffer from userspace. + * @buffer: data buffer for file. + * @userbuf: data from user. + * @count: number of bytes in @userbuf. + * + * Allocate @buffer->page if it hasn't been already, then + * copy the user-supplied buffer into it. + */ + +static int +fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count) +{ + int error; + + if (!buffer->page) + buffer->page = (char *)get_zeroed_page(GFP_KERNEL); + if (!buffer->page) + return -ENOMEM; + + if (count >= PAGE_SIZE) + count = PAGE_SIZE - 1; + error = copy_from_user(buffer->page,buf,count); + buffer->needs_read_fill = 1; + return error ? -EFAULT : count; +} + + +/** + * flush_write_buffer - push buffer to kobject. + * @file: file pointer. + * @buffer: data buffer for file. + * + * Get the correct pointers for the kobject and the attribute we're + * dealing with, then call the store() method for the attribute, + * passing the buffer that we acquired in fill_write_buffer(). + */ + +static int +flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count) +{ + struct attribute * attr = to_attr(dentry); + struct kobject * kobj = to_kobj(dentry->d_parent); + struct sysfs_ops * ops = buffer->ops; + + return ops->store(kobj,attr,buffer->page,count); +} + + +/** + * sysfs_write_file - write an attribute. + * @file: file pointer + * @buf: data to write + * @count: number of bytes + * @ppos: starting offset + * + * Similar to sysfs_read_file(), though working in the opposite direction. + * We allocate and fill the data from the user in fill_write_buffer(), + * then push it to the kobject in flush_write_buffer(). + * There is no easy way for us to know if userspace is only doing a partial + * write, so we don't support them. We expect the entire buffer to come + * on the first write. + * Hint: if you're writing a value, first read the file, modify only the + * the value you're changing, then write entire buffer back. + */ + +static ssize_t +sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos) +{ + struct sysfs_buffer * buffer = file->private_data; + ssize_t len; + + down(&buffer->sem); + len = fill_write_buffer(buffer, buf, count); + if (len > 0) + len = flush_write_buffer(file->f_dentry, buffer, len); + if (len > 0) + *ppos += len; + up(&buffer->sem); + return len; +} + +static int check_perm(struct inode * inode, struct file * file) +{ + struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent); + struct attribute * attr = to_attr(file->f_dentry); + struct sysfs_buffer * buffer; + struct sysfs_ops * ops = NULL; + int error = 0; + + if (!kobj || !attr) + goto Einval; + + /* Grab the module reference for this attribute if we have one */ + if (!try_module_get(attr->owner)) { + error = -ENODEV; + goto Done; + } + + /* if the kobject has no ktype, then we assume that it is a subsystem + * itself, and use ops for it. + */ + if (kobj->kset && kobj->kset->ktype) + ops = kobj->kset->ktype->sysfs_ops; + else if (kobj->ktype) + ops = kobj->ktype->sysfs_ops; + else + ops = &subsys_sysfs_ops; + + /* No sysfs operations, either from having no subsystem, + * or the subsystem have no operations. + */ + if (!ops) + goto Eaccess; + + /* 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; + + } + + /* File needs read support. + * The inode's perms must say it's ok, and we there + * must be a show method for it. + */ + if (file->f_mode & FMODE_READ) { + if (!(inode->i_mode & S_IRUGO) || !ops->show) + goto Eaccess; + } + + /* No error? Great, allocate a buffer for the file, and store it + * it in file->private_data for easy access. + */ + buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL); + if (buffer) { + memset(buffer,0,sizeof(struct sysfs_buffer)); + init_MUTEX(&buffer->sem); + buffer->needs_read_fill = 1; + buffer->ops = ops; + file->private_data = buffer; + } else + error = -ENOMEM; + goto Done; + + Einval: + error = -EINVAL; + goto Done; + Eaccess: + error = -EACCES; + module_put(attr->owner); + Done: + if (error && kobj) + kobject_put(kobj); + return error; +} + +static int sysfs_open_file(struct inode * inode, struct file * filp) +{ + return check_perm(inode,filp); +} + +static int sysfs_release(struct inode * inode, struct file * filp) +{ + struct kobject * kobj = to_kobj(filp->f_dentry->d_parent); + struct attribute * attr = to_attr(filp->f_dentry); + struct module * owner = attr->owner; + struct sysfs_buffer * buffer = filp->private_data; + + if (kobj) + kobject_put(kobj); + /* After this point, attr should not be accessed. */ + module_put(owner); + + if (buffer) { + if (buffer->page) + free_page((unsigned long)buffer->page); + kfree(buffer); + } + return 0; +} + +struct file_operations sysfs_file_operations = { + .read = sysfs_read_file, + .write = sysfs_write_file, + .llseek = generic_file_llseek, + .open = sysfs_open_file, + .release = sysfs_release, +}; + + +int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type) +{ + struct sysfs_dirent * parent_sd = dir->d_fsdata; + umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG; + int error = 0; + + down(&dir->d_inode->i_sem); + error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type); + up(&dir->d_inode->i_sem); + + return error; +} + + +/** + * sysfs_create_file - create an attribute file for an object. + * @kobj: object we're creating for. + * @attr: atrribute descriptor. + */ + +int sysfs_create_file(struct kobject * kobj, const struct attribute * attr) +{ + BUG_ON(!kobj || !kobj->dentry || !attr); + + return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR); + +} + + +/** + * sysfs_update_file - update the modified timestamp on an object attribute. + * @kobj: object we're acting for. + * @attr: attribute descriptor. + * + * Also call dnotify for the dentry, which lots of userspace programs + * use. + */ +int sysfs_update_file(struct kobject * kobj, const struct attribute * attr) +{ + struct dentry * dir = kobj->dentry; + struct dentry * victim; + int res = -ENOENT; + + down(&dir->d_inode->i_sem); + victim = sysfs_get_dentry(dir, attr->name); + if (!IS_ERR(victim)) { + /* make sure dentry is really there */ + if (victim->d_inode && + (victim->d_parent->d_inode == dir->d_inode)) { + victim->d_inode->i_mtime = CURRENT_TIME; + dnotify_parent(victim, DN_MODIFY); + + /** + * Drop reference from initial sysfs_get_dentry(). + */ + dput(victim); + res = 0; + } else + d_drop(victim); + + /** + * Drop the reference acquired from sysfs_get_dentry() above. + */ + dput(victim); + } + up(&dir->d_inode->i_sem); + + return res; +} + + +/** + * sysfs_remove_file - remove an object attribute. + * @kobj: object we're acting for. + * @attr: attribute descriptor. + * + * Hash the attribute name and kill the victim. + */ + +void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr) +{ + sysfs_hash_and_remove(kobj->dentry,attr->name); +} + + +EXPORT_SYMBOL_GPL(sysfs_create_file); +EXPORT_SYMBOL_GPL(sysfs_remove_file); +EXPORT_SYMBOL_GPL(sysfs_update_file); + |