![Tejun Heo](/assets/img/avatar_default.png)
13c589d5b0
("sysfs: use seq_file when reading regular files")
converted regular sysfs files to use seq_file. The commit substituted
generic_file_llseek() with seq_lseek() for llseek implementation.
Before the change, all regular sysfs files were allowed to seek to any
position in [0, PAGE_SIZE] as the file size is always PAGE_SIZE and
generic_file_llseek() allows any seeking inside the range under file
size; however, seq_lseek()'s behavior is different. It traverses the
output by repeatedly invoking ->show() until it reaches the target
offset or traversal indicates EOF. As seq_files are fully dynamic and
may not end at all, it doesn't support seeking from the end
(SEEK_END).
Apparently, there are userland tools which uses SEEK_END to discover
the buffer size to use and the switch to seq_lseek() disturbs them as
SEEK_END fails with -EINVAL.
The only benefits of using seq_lseek() instead of
generic_file_llseek() are
* Early failure. If traversing to certain file position should fail,
seq_lseek() will report such failures on lseek(2) instead of the
following read/write operations.
* EOF detection. While SEEK_END is not supported, SEEK_SET/CUR +
large offset can be used to detect eof - eof at the time of the seek
anyway as the file size may change dynamically.
Both aren't necessary for sysfs or prospect kernfs users. Revert to
genefic_file_llseek() and preserve the original behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Link: https://lkml.kernel.org/r/20131031114358.GA5551@osiris
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1106 lines
26 KiB
C
1106 lines
26 KiB
C
/*
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* fs/sysfs/file.c - sysfs regular (text) file implementation
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#include <linux/module.h>
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#include <linux/kobject.h>
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#include <linux/kallsyms.h>
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#include <linux/slab.h>
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#include <linux/fsnotify.h>
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#include <linux/namei.h>
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#include <linux/poll.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/limits.h>
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#include <linux/uaccess.h>
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#include <linux/seq_file.h>
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#include <linux/mm.h>
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#include "sysfs.h"
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/*
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* There's one sysfs_open_file for each open file and one sysfs_open_dirent
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* for each sysfs_dirent with one or more open files.
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*
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* sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open is
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* protected by sysfs_open_dirent_lock.
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*
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* filp->private_data points to seq_file whose ->private points to
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* sysfs_open_file. sysfs_open_files are chained at
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* sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
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*/
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static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
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static DEFINE_MUTEX(sysfs_open_file_mutex);
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struct sysfs_open_dirent {
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atomic_t refcnt;
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atomic_t event;
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wait_queue_head_t poll;
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struct list_head files; /* goes through sysfs_open_file.list */
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};
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struct sysfs_open_file {
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struct sysfs_dirent *sd;
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struct file *file;
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struct mutex mutex;
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int event;
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struct list_head list;
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bool mmapped;
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const struct vm_operations_struct *vm_ops;
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};
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static bool sysfs_is_bin(struct sysfs_dirent *sd)
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{
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return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
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}
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static struct sysfs_open_file *sysfs_of(struct file *file)
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{
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return ((struct seq_file *)file->private_data)->private;
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}
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/*
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* Determine ktype->sysfs_ops for the given sysfs_dirent. This function
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* must be called while holding an active reference.
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*/
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static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
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{
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struct kobject *kobj = sd->s_parent->s_dir.kobj;
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if (!sysfs_ignore_lockdep(sd))
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lockdep_assert_held(sd);
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return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
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}
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/*
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* Reads on sysfs are handled through seq_file, which takes care of hairy
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* details like buffering and seeking. The following function pipes
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* sysfs_ops->show() result through seq_file.
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*/
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static int sysfs_seq_show(struct seq_file *sf, void *v)
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{
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struct sysfs_open_file *of = sf->private;
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struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
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const struct sysfs_ops *ops;
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char *buf;
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ssize_t count;
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/* acquire buffer and ensure that it's >= PAGE_SIZE */
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count = seq_get_buf(sf, &buf);
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if (count < PAGE_SIZE) {
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seq_commit(sf, -1);
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return 0;
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}
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/*
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* Need @of->sd for attr and ops, its parent for kobj. @of->mutex
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* nests outside active ref and is just to ensure that the ops
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* aren't called concurrently for the same open file.
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*/
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mutex_lock(&of->mutex);
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if (!sysfs_get_active(of->sd)) {
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mutex_unlock(&of->mutex);
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return -ENODEV;
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}
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of->event = atomic_read(&of->sd->s_attr.open->event);
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/*
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* Lookup @ops and invoke show(). Control may reach here via seq
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* file lseek even if @ops->show() isn't implemented.
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*/
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ops = sysfs_file_ops(of->sd);
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if (ops->show)
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count = ops->show(kobj, of->sd->s_attr.attr, buf);
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else
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count = 0;
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sysfs_put_active(of->sd);
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mutex_unlock(&of->mutex);
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if (count < 0)
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return count;
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/*
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* The code works fine with PAGE_SIZE return but it's likely to
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* indicate truncated result or overflow in normal use cases.
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*/
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if (count >= (ssize_t)PAGE_SIZE) {
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print_symbol("fill_read_buffer: %s returned bad count\n",
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(unsigned long)ops->show);
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/* Try to struggle along */
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count = PAGE_SIZE - 1;
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}
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seq_commit(sf, count);
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return 0;
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}
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/*
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* Read method for bin files. As reading a bin file can have side-effects,
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* the exact offset and bytes specified in read(2) call should be passed to
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* the read callback making it difficult to use seq_file. Implement
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* simplistic custom buffering for bin files.
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*/
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static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
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size_t bytes, loff_t *off)
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{
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struct sysfs_open_file *of = sysfs_of(file);
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struct bin_attribute *battr = of->sd->s_attr.bin_attr;
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struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
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loff_t size = file_inode(file)->i_size;
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int count = min_t(size_t, bytes, PAGE_SIZE);
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loff_t offs = *off;
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char *buf;
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if (!bytes)
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return 0;
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if (size) {
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if (offs > size)
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return 0;
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if (offs + count > size)
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count = size - offs;
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}
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buf = kmalloc(count, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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/* need of->sd for battr, its parent for kobj */
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mutex_lock(&of->mutex);
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if (!sysfs_get_active(of->sd)) {
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count = -ENODEV;
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mutex_unlock(&of->mutex);
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goto out_free;
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}
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if (battr->read)
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count = battr->read(file, kobj, battr, buf, offs, count);
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else
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count = -EIO;
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sysfs_put_active(of->sd);
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mutex_unlock(&of->mutex);
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if (count < 0)
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goto out_free;
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if (copy_to_user(userbuf, buf, count)) {
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count = -EFAULT;
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goto out_free;
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}
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pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
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*off = offs + count;
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out_free:
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kfree(buf);
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return count;
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}
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/**
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* flush_write_buffer - push buffer to kobject
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* @of: open file
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* @buf: data buffer for file
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* @off: file offset to write to
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* @count: number of bytes
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*
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* Get the correct pointers for the kobject and the attribute we're dealing
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* with, then call the store() method for it with @buf.
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*/
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static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
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size_t count)
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{
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struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
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int rc = 0;
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/*
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* Need @of->sd for attr and ops, its parent for kobj. @of->mutex
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* nests outside active ref and is just to ensure that the ops
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* aren't called concurrently for the same open file.
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*/
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mutex_lock(&of->mutex);
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if (!sysfs_get_active(of->sd)) {
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mutex_unlock(&of->mutex);
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return -ENODEV;
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}
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if (sysfs_is_bin(of->sd)) {
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struct bin_attribute *battr = of->sd->s_attr.bin_attr;
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rc = -EIO;
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if (battr->write)
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rc = battr->write(of->file, kobj, battr, buf, off,
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count);
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} else {
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const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
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rc = ops->store(kobj, of->sd->s_attr.attr, buf, count);
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}
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sysfs_put_active(of->sd);
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mutex_unlock(&of->mutex);
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return rc;
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}
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/**
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* sysfs_write_file - write an attribute
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* @file: file pointer
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* @user_buf: data to write
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* @count: number of bytes
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* @ppos: starting offset
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*
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* Copy data in from userland and pass it to the matching
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* sysfs_ops->store() by invoking flush_write_buffer().
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*
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* There is no easy way for us to know if userspace is only doing a partial
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* write, so we don't support them. We expect the entire buffer to come on
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* the first write. Hint: if you're writing a value, first read the file,
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* modify only the the value you're changing, then write entire buffer
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* back.
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*/
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static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct sysfs_open_file *of = sysfs_of(file);
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ssize_t len = min_t(size_t, count, PAGE_SIZE);
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loff_t size = file_inode(file)->i_size;
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char *buf;
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if (sysfs_is_bin(of->sd) && size) {
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if (size <= *ppos)
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return 0;
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len = min_t(ssize_t, len, size - *ppos);
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}
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if (!len)
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return 0;
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buf = kmalloc(len + 1, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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if (copy_from_user(buf, user_buf, len)) {
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len = -EFAULT;
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goto out_free;
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}
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buf[len] = '\0'; /* guarantee string termination */
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len = flush_write_buffer(of, buf, *ppos, len);
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if (len > 0)
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*ppos += len;
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out_free:
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kfree(buf);
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return len;
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}
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static void sysfs_bin_vma_open(struct vm_area_struct *vma)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
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if (!of->vm_ops)
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return;
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if (!sysfs_get_active(of->sd))
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return;
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if (of->vm_ops->open)
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of->vm_ops->open(vma);
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sysfs_put_active(of->sd);
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}
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static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
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int ret;
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if (!of->vm_ops)
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return VM_FAULT_SIGBUS;
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if (!sysfs_get_active(of->sd))
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return VM_FAULT_SIGBUS;
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ret = VM_FAULT_SIGBUS;
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if (of->vm_ops->fault)
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ret = of->vm_ops->fault(vma, vmf);
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sysfs_put_active(of->sd);
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return ret;
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}
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static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
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struct vm_fault *vmf)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
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int ret;
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if (!of->vm_ops)
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return VM_FAULT_SIGBUS;
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if (!sysfs_get_active(of->sd))
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return VM_FAULT_SIGBUS;
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ret = 0;
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if (of->vm_ops->page_mkwrite)
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ret = of->vm_ops->page_mkwrite(vma, vmf);
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else
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file_update_time(file);
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sysfs_put_active(of->sd);
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return ret;
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}
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static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
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void *buf, int len, int write)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
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int ret;
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if (!of->vm_ops)
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return -EINVAL;
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if (!sysfs_get_active(of->sd))
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return -EINVAL;
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ret = -EINVAL;
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if (of->vm_ops->access)
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ret = of->vm_ops->access(vma, addr, buf, len, write);
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sysfs_put_active(of->sd);
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return ret;
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}
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#ifdef CONFIG_NUMA
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static int sysfs_bin_set_policy(struct vm_area_struct *vma,
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struct mempolicy *new)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
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int ret;
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|
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if (!of->vm_ops)
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return 0;
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|
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if (!sysfs_get_active(of->sd))
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return -EINVAL;
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ret = 0;
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if (of->vm_ops->set_policy)
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ret = of->vm_ops->set_policy(vma, new);
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sysfs_put_active(of->sd);
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return ret;
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}
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static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
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unsigned long addr)
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{
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struct file *file = vma->vm_file;
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struct sysfs_open_file *of = sysfs_of(file);
|
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struct mempolicy *pol;
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|
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if (!of->vm_ops)
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return vma->vm_policy;
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|
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if (!sysfs_get_active(of->sd))
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return vma->vm_policy;
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|
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pol = vma->vm_policy;
|
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if (of->vm_ops->get_policy)
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pol = of->vm_ops->get_policy(vma, addr);
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|
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sysfs_put_active(of->sd);
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return pol;
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}
|
|
|
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static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
|
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const nodemask_t *to, unsigned long flags)
|
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{
|
|
struct file *file = vma->vm_file;
|
|
struct sysfs_open_file *of = sysfs_of(file);
|
|
int ret;
|
|
|
|
if (!of->vm_ops)
|
|
return 0;
|
|
|
|
if (!sysfs_get_active(of->sd))
|
|
return 0;
|
|
|
|
ret = 0;
|
|
if (of->vm_ops->migrate)
|
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ret = of->vm_ops->migrate(vma, from, to, flags);
|
|
|
|
sysfs_put_active(of->sd);
|
|
return ret;
|
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}
|
|
#endif
|
|
|
|
static const struct vm_operations_struct sysfs_bin_vm_ops = {
|
|
.open = sysfs_bin_vma_open,
|
|
.fault = sysfs_bin_fault,
|
|
.page_mkwrite = sysfs_bin_page_mkwrite,
|
|
.access = sysfs_bin_access,
|
|
#ifdef CONFIG_NUMA
|
|
.set_policy = sysfs_bin_set_policy,
|
|
.get_policy = sysfs_bin_get_policy,
|
|
.migrate = sysfs_bin_migrate,
|
|
#endif
|
|
};
|
|
|
|
static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
struct sysfs_open_file *of = sysfs_of(file);
|
|
struct bin_attribute *battr = of->sd->s_attr.bin_attr;
|
|
struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
|
|
int rc;
|
|
|
|
mutex_lock(&of->mutex);
|
|
|
|
/* need of->sd for battr, its parent for kobj */
|
|
rc = -ENODEV;
|
|
if (!sysfs_get_active(of->sd))
|
|
goto out_unlock;
|
|
|
|
if (!battr->mmap)
|
|
goto out_put;
|
|
|
|
rc = battr->mmap(file, kobj, battr, vma);
|
|
if (rc)
|
|
goto out_put;
|
|
|
|
/*
|
|
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
|
|
* to satisfy versions of X which crash if the mmap fails: that
|
|
* substitutes a new vm_file, and we don't then want bin_vm_ops.
|
|
*/
|
|
if (vma->vm_file != file)
|
|
goto out_put;
|
|
|
|
rc = -EINVAL;
|
|
if (of->mmapped && of->vm_ops != vma->vm_ops)
|
|
goto out_put;
|
|
|
|
/*
|
|
* It is not possible to successfully wrap close.
|
|
* So error if someone is trying to use close.
|
|
*/
|
|
rc = -EINVAL;
|
|
if (vma->vm_ops && vma->vm_ops->close)
|
|
goto out_put;
|
|
|
|
rc = 0;
|
|
of->mmapped = 1;
|
|
of->vm_ops = vma->vm_ops;
|
|
vma->vm_ops = &sysfs_bin_vm_ops;
|
|
out_put:
|
|
sysfs_put_active(of->sd);
|
|
out_unlock:
|
|
mutex_unlock(&of->mutex);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* sysfs_get_open_dirent - get or create sysfs_open_dirent
|
|
* @sd: target sysfs_dirent
|
|
* @of: sysfs_open_file for this instance of open
|
|
*
|
|
* If @sd->s_attr.open exists, increment its reference count;
|
|
* otherwise, create one. @of is chained to the files list.
|
|
*
|
|
* LOCKING:
|
|
* Kernel thread context (may sleep).
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
|
|
struct sysfs_open_file *of)
|
|
{
|
|
struct sysfs_open_dirent *od, *new_od = NULL;
|
|
|
|
retry:
|
|
mutex_lock(&sysfs_open_file_mutex);
|
|
spin_lock_irq(&sysfs_open_dirent_lock);
|
|
|
|
if (!sd->s_attr.open && new_od) {
|
|
sd->s_attr.open = new_od;
|
|
new_od = NULL;
|
|
}
|
|
|
|
od = sd->s_attr.open;
|
|
if (od) {
|
|
atomic_inc(&od->refcnt);
|
|
list_add_tail(&of->list, &od->files);
|
|
}
|
|
|
|
spin_unlock_irq(&sysfs_open_dirent_lock);
|
|
mutex_unlock(&sysfs_open_file_mutex);
|
|
|
|
if (od) {
|
|
kfree(new_od);
|
|
return 0;
|
|
}
|
|
|
|
/* not there, initialize a new one and retry */
|
|
new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
|
|
if (!new_od)
|
|
return -ENOMEM;
|
|
|
|
atomic_set(&new_od->refcnt, 0);
|
|
atomic_set(&new_od->event, 1);
|
|
init_waitqueue_head(&new_od->poll);
|
|
INIT_LIST_HEAD(&new_od->files);
|
|
goto retry;
|
|
}
|
|
|
|
/**
|
|
* sysfs_put_open_dirent - put sysfs_open_dirent
|
|
* @sd: target sysfs_dirent
|
|
* @of: associated sysfs_open_file
|
|
*
|
|
* Put @sd->s_attr.open and unlink @of from the files list. If
|
|
* reference count reaches zero, disassociate and free it.
|
|
*
|
|
* LOCKING:
|
|
* None.
|
|
*/
|
|
static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
|
|
struct sysfs_open_file *of)
|
|
{
|
|
struct sysfs_open_dirent *od = sd->s_attr.open;
|
|
unsigned long flags;
|
|
|
|
mutex_lock(&sysfs_open_file_mutex);
|
|
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
|
|
|
|
if (of)
|
|
list_del(&of->list);
|
|
|
|
if (atomic_dec_and_test(&od->refcnt))
|
|
sd->s_attr.open = NULL;
|
|
else
|
|
od = NULL;
|
|
|
|
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
|
|
mutex_unlock(&sysfs_open_file_mutex);
|
|
|
|
kfree(od);
|
|
}
|
|
|
|
static int sysfs_open_file(struct inode *inode, struct file *file)
|
|
{
|
|
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
|
|
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
|
|
struct sysfs_open_file *of;
|
|
bool has_read, has_write;
|
|
int error = -EACCES;
|
|
|
|
/* need attr_sd for attr and ops, its parent for kobj */
|
|
if (!sysfs_get_active(attr_sd))
|
|
return -ENODEV;
|
|
|
|
if (sysfs_is_bin(attr_sd)) {
|
|
struct bin_attribute *battr = attr_sd->s_attr.bin_attr;
|
|
|
|
has_read = battr->read || battr->mmap;
|
|
has_write = battr->write || battr->mmap;
|
|
} else {
|
|
const struct sysfs_ops *ops = sysfs_file_ops(attr_sd);
|
|
|
|
/* every kobject with an attribute needs a ktype assigned */
|
|
if (WARN(!ops, KERN_ERR
|
|
"missing sysfs attribute operations for kobject: %s\n",
|
|
kobject_name(kobj)))
|
|
goto err_out;
|
|
|
|
has_read = ops->show;
|
|
has_write = ops->store;
|
|
}
|
|
|
|
/* check perms and supported operations */
|
|
if ((file->f_mode & FMODE_WRITE) &&
|
|
(!(inode->i_mode & S_IWUGO) || !has_write))
|
|
goto err_out;
|
|
|
|
if ((file->f_mode & FMODE_READ) &&
|
|
(!(inode->i_mode & S_IRUGO) || !has_read))
|
|
goto err_out;
|
|
|
|
/* allocate a sysfs_open_file for the file */
|
|
error = -ENOMEM;
|
|
of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
|
|
if (!of)
|
|
goto err_out;
|
|
|
|
mutex_init(&of->mutex);
|
|
of->sd = attr_sd;
|
|
of->file = file;
|
|
|
|
/*
|
|
* Always instantiate seq_file even if read access doesn't use
|
|
* seq_file or is not requested. This unifies private data access
|
|
* and readable regular files are the vast majority anyway.
|
|
*/
|
|
if (sysfs_is_bin(attr_sd))
|
|
error = single_open(file, NULL, of);
|
|
else
|
|
error = single_open(file, sysfs_seq_show, of);
|
|
if (error)
|
|
goto err_free;
|
|
|
|
/* seq_file clears PWRITE unconditionally, restore it if WRITE */
|
|
if (file->f_mode & FMODE_WRITE)
|
|
file->f_mode |= FMODE_PWRITE;
|
|
|
|
/* make sure we have open dirent struct */
|
|
error = sysfs_get_open_dirent(attr_sd, of);
|
|
if (error)
|
|
goto err_close;
|
|
|
|
/* open succeeded, put active references */
|
|
sysfs_put_active(attr_sd);
|
|
return 0;
|
|
|
|
err_close:
|
|
single_release(inode, file);
|
|
err_free:
|
|
kfree(of);
|
|
err_out:
|
|
sysfs_put_active(attr_sd);
|
|
return error;
|
|
}
|
|
|
|
static int sysfs_release(struct inode *inode, struct file *filp)
|
|
{
|
|
struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
|
|
struct sysfs_open_file *of = sysfs_of(filp);
|
|
|
|
sysfs_put_open_dirent(sd, of);
|
|
single_release(inode, filp);
|
|
kfree(of);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
|
|
{
|
|
struct sysfs_open_dirent *od;
|
|
struct sysfs_open_file *of;
|
|
|
|
if (!sysfs_is_bin(sd))
|
|
return;
|
|
|
|
spin_lock_irq(&sysfs_open_dirent_lock);
|
|
od = sd->s_attr.open;
|
|
if (od)
|
|
atomic_inc(&od->refcnt);
|
|
spin_unlock_irq(&sysfs_open_dirent_lock);
|
|
if (!od)
|
|
return;
|
|
|
|
mutex_lock(&sysfs_open_file_mutex);
|
|
list_for_each_entry(of, &od->files, list) {
|
|
struct inode *inode = file_inode(of->file);
|
|
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
|
|
}
|
|
mutex_unlock(&sysfs_open_file_mutex);
|
|
|
|
sysfs_put_open_dirent(sd, NULL);
|
|
}
|
|
|
|
/* Sysfs attribute files are pollable. The idea is that you read
|
|
* the content and then you use 'poll' or 'select' to wait for
|
|
* the content to change. When the content changes (assuming the
|
|
* manager for the kobject supports notification), poll will
|
|
* return POLLERR|POLLPRI, and select will return the fd whether
|
|
* it is waiting for read, write, or exceptions.
|
|
* Once poll/select indicates that the value has changed, you
|
|
* need to close and re-open the file, or seek to 0 and read again.
|
|
* Reminder: this only works for attributes which actively support
|
|
* it, and it is not possible to test an attribute from userspace
|
|
* to see if it supports poll (Neither 'poll' nor 'select' return
|
|
* an appropriate error code). When in doubt, set a suitable timeout value.
|
|
*/
|
|
static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
|
|
{
|
|
struct sysfs_open_file *of = sysfs_of(filp);
|
|
struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
|
|
struct sysfs_open_dirent *od = attr_sd->s_attr.open;
|
|
|
|
/* need parent for the kobj, grab both */
|
|
if (!sysfs_get_active(attr_sd))
|
|
goto trigger;
|
|
|
|
poll_wait(filp, &od->poll, wait);
|
|
|
|
sysfs_put_active(attr_sd);
|
|
|
|
if (of->event != atomic_read(&od->event))
|
|
goto trigger;
|
|
|
|
return DEFAULT_POLLMASK;
|
|
|
|
trigger:
|
|
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
|
|
}
|
|
|
|
void sysfs_notify_dirent(struct sysfs_dirent *sd)
|
|
{
|
|
struct sysfs_open_dirent *od;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
|
|
|
|
if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
|
|
od = sd->s_attr.open;
|
|
if (od) {
|
|
atomic_inc(&od->event);
|
|
wake_up_interruptible(&od->poll);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
|
|
|
|
void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
|
|
{
|
|
struct sysfs_dirent *sd = k->sd;
|
|
|
|
mutex_lock(&sysfs_mutex);
|
|
|
|
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);
|
|
|
|
mutex_unlock(&sysfs_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_notify);
|
|
|
|
const struct file_operations sysfs_file_operations = {
|
|
.read = seq_read,
|
|
.write = sysfs_write_file,
|
|
.llseek = generic_file_llseek,
|
|
.open = sysfs_open_file,
|
|
.release = sysfs_release,
|
|
.poll = sysfs_poll,
|
|
};
|
|
|
|
const struct file_operations sysfs_bin_operations = {
|
|
.read = sysfs_bin_read,
|
|
.write = sysfs_write_file,
|
|
.llseek = generic_file_llseek,
|
|
.mmap = sysfs_bin_mmap,
|
|
.open = sysfs_open_file,
|
|
.release = sysfs_release,
|
|
.poll = sysfs_poll,
|
|
};
|
|
|
|
int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
|
|
const struct attribute *attr, int type,
|
|
umode_t amode, const void *ns)
|
|
{
|
|
umode_t mode = (amode & S_IALLUGO) | S_IFREG;
|
|
struct sysfs_addrm_cxt acxt;
|
|
struct sysfs_dirent *sd;
|
|
int rc;
|
|
|
|
sd = sysfs_new_dirent(attr->name, mode, type);
|
|
if (!sd)
|
|
return -ENOMEM;
|
|
|
|
sd->s_ns = ns;
|
|
sd->s_attr.attr = (void *)attr;
|
|
sysfs_dirent_init_lockdep(sd);
|
|
|
|
sysfs_addrm_start(&acxt);
|
|
rc = sysfs_add_one(&acxt, sd, dir_sd);
|
|
sysfs_addrm_finish(&acxt);
|
|
|
|
if (rc)
|
|
sysfs_put(sd);
|
|
|
|
return rc;
|
|
}
|
|
|
|
|
|
int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
|
|
int type)
|
|
{
|
|
return sysfs_add_file_mode_ns(dir_sd, attr, type, attr->mode, NULL);
|
|
}
|
|
|
|
/**
|
|
* sysfs_create_file_ns - create an attribute file for an object with custom ns
|
|
* @kobj: object we're creating for
|
|
* @attr: attribute descriptor
|
|
* @ns: namespace the new file should belong to
|
|
*/
|
|
int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
|
|
const void *ns)
|
|
{
|
|
BUG_ON(!kobj || !kobj->sd || !attr);
|
|
|
|
return sysfs_add_file_mode_ns(kobj->sd, attr, SYSFS_KOBJ_ATTR,
|
|
attr->mode, ns);
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
|
|
|
|
int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
|
|
{
|
|
int err = 0;
|
|
int i;
|
|
|
|
for (i = 0; ptr[i] && !err; i++)
|
|
err = sysfs_create_file(kobj, ptr[i]);
|
|
if (err)
|
|
while (--i >= 0)
|
|
sysfs_remove_file(kobj, ptr[i]);
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_create_files);
|
|
|
|
/**
|
|
* sysfs_add_file_to_group - add an attribute file to a pre-existing group.
|
|
* @kobj: object we're acting for.
|
|
* @attr: attribute descriptor.
|
|
* @group: group name.
|
|
*/
|
|
int sysfs_add_file_to_group(struct kobject *kobj,
|
|
const struct attribute *attr, const char *group)
|
|
{
|
|
struct sysfs_dirent *dir_sd;
|
|
int error;
|
|
|
|
if (group)
|
|
dir_sd = sysfs_get_dirent(kobj->sd, group);
|
|
else
|
|
dir_sd = sysfs_get(kobj->sd);
|
|
|
|
if (!dir_sd)
|
|
return -ENOENT;
|
|
|
|
error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
|
|
sysfs_put(dir_sd);
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
|
|
|
|
/**
|
|
* sysfs_chmod_file - update the modified mode value on an object attribute.
|
|
* @kobj: object we're acting for.
|
|
* @attr: attribute descriptor.
|
|
* @mode: file permissions.
|
|
*
|
|
*/
|
|
int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
|
|
umode_t mode)
|
|
{
|
|
struct sysfs_dirent *sd;
|
|
struct iattr newattrs;
|
|
int rc;
|
|
|
|
mutex_lock(&sysfs_mutex);
|
|
|
|
rc = -ENOENT;
|
|
sd = sysfs_find_dirent(kobj->sd, attr->name, NULL);
|
|
if (!sd)
|
|
goto out;
|
|
|
|
newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
|
|
newattrs.ia_valid = ATTR_MODE;
|
|
rc = sysfs_sd_setattr(sd, &newattrs);
|
|
|
|
out:
|
|
mutex_unlock(&sysfs_mutex);
|
|
return rc;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_chmod_file);
|
|
|
|
/**
|
|
* sysfs_remove_file_ns - remove an object attribute with a custom ns tag
|
|
* @kobj: object we're acting for
|
|
* @attr: attribute descriptor
|
|
* @ns: namespace tag of the file to remove
|
|
*
|
|
* Hash the attribute name and namespace tag and kill the victim.
|
|
*/
|
|
void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
|
|
const void *ns)
|
|
{
|
|
struct sysfs_dirent *dir_sd = kobj->sd;
|
|
|
|
sysfs_hash_and_remove(dir_sd, attr->name, ns);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
|
|
|
|
void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
|
|
{
|
|
int i;
|
|
for (i = 0; ptr[i]; i++)
|
|
sysfs_remove_file(kobj, ptr[i]);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_remove_files);
|
|
|
|
/**
|
|
* sysfs_remove_file_from_group - remove an attribute file from a group.
|
|
* @kobj: object we're acting for.
|
|
* @attr: attribute descriptor.
|
|
* @group: group name.
|
|
*/
|
|
void sysfs_remove_file_from_group(struct kobject *kobj,
|
|
const struct attribute *attr, const char *group)
|
|
{
|
|
struct sysfs_dirent *dir_sd;
|
|
|
|
if (group)
|
|
dir_sd = sysfs_get_dirent(kobj->sd, group);
|
|
else
|
|
dir_sd = sysfs_get(kobj->sd);
|
|
if (dir_sd) {
|
|
sysfs_hash_and_remove(dir_sd, attr->name, NULL);
|
|
sysfs_put(dir_sd);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
|
|
|
|
/**
|
|
* sysfs_create_bin_file - create binary file for object.
|
|
* @kobj: object.
|
|
* @attr: attribute descriptor.
|
|
*/
|
|
int sysfs_create_bin_file(struct kobject *kobj,
|
|
const struct bin_attribute *attr)
|
|
{
|
|
BUG_ON(!kobj || !kobj->sd || !attr);
|
|
|
|
return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
|
|
|
|
/**
|
|
* sysfs_remove_bin_file - remove binary file for object.
|
|
* @kobj: object.
|
|
* @attr: attribute descriptor.
|
|
*/
|
|
void sysfs_remove_bin_file(struct kobject *kobj,
|
|
const struct bin_attribute *attr)
|
|
{
|
|
sysfs_hash_and_remove(kobj->sd, attr->attr.name, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
|
|
|
|
struct sysfs_schedule_callback_struct {
|
|
struct list_head workq_list;
|
|
struct kobject *kobj;
|
|
void (*func)(void *);
|
|
void *data;
|
|
struct module *owner;
|
|
struct work_struct work;
|
|
};
|
|
|
|
static struct workqueue_struct *sysfs_workqueue;
|
|
static DEFINE_MUTEX(sysfs_workq_mutex);
|
|
static LIST_HEAD(sysfs_workq);
|
|
static void sysfs_schedule_callback_work(struct work_struct *work)
|
|
{
|
|
struct sysfs_schedule_callback_struct *ss = container_of(work,
|
|
struct sysfs_schedule_callback_struct, work);
|
|
|
|
(ss->func)(ss->data);
|
|
kobject_put(ss->kobj);
|
|
module_put(ss->owner);
|
|
mutex_lock(&sysfs_workq_mutex);
|
|
list_del(&ss->workq_list);
|
|
mutex_unlock(&sysfs_workq_mutex);
|
|
kfree(ss);
|
|
}
|
|
|
|
/**
|
|
* sysfs_schedule_callback - helper to schedule a callback for a kobject
|
|
* @kobj: object we're acting for.
|
|
* @func: callback function to invoke later.
|
|
* @data: argument to pass to @func.
|
|
* @owner: module owning the callback code
|
|
*
|
|
* sysfs attribute methods must not unregister themselves or their parent
|
|
* kobject (which would amount to the same thing). Attempts to do so will
|
|
* deadlock, since unregistration is mutually exclusive with driver
|
|
* callbacks.
|
|
*
|
|
* Instead methods can call this routine, which will attempt to allocate
|
|
* and schedule a workqueue request to call back @func with @data as its
|
|
* argument in the workqueue's process context. @kobj will be pinned
|
|
* until @func returns.
|
|
*
|
|
* Returns 0 if the request was submitted, -ENOMEM if storage could not
|
|
* be allocated, -ENODEV if a reference to @owner isn't available,
|
|
* -EAGAIN if a callback has already been scheduled for @kobj.
|
|
*/
|
|
int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
|
|
void *data, struct module *owner)
|
|
{
|
|
struct sysfs_schedule_callback_struct *ss, *tmp;
|
|
|
|
if (!try_module_get(owner))
|
|
return -ENODEV;
|
|
|
|
mutex_lock(&sysfs_workq_mutex);
|
|
list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
|
|
if (ss->kobj == kobj) {
|
|
module_put(owner);
|
|
mutex_unlock(&sysfs_workq_mutex);
|
|
return -EAGAIN;
|
|
}
|
|
mutex_unlock(&sysfs_workq_mutex);
|
|
|
|
if (sysfs_workqueue == NULL) {
|
|
sysfs_workqueue = create_singlethread_workqueue("sysfsd");
|
|
if (sysfs_workqueue == NULL) {
|
|
module_put(owner);
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
|
|
ss = kmalloc(sizeof(*ss), GFP_KERNEL);
|
|
if (!ss) {
|
|
module_put(owner);
|
|
return -ENOMEM;
|
|
}
|
|
kobject_get(kobj);
|
|
ss->kobj = kobj;
|
|
ss->func = func;
|
|
ss->data = data;
|
|
ss->owner = owner;
|
|
INIT_WORK(&ss->work, sysfs_schedule_callback_work);
|
|
INIT_LIST_HEAD(&ss->workq_list);
|
|
mutex_lock(&sysfs_workq_mutex);
|
|
list_add_tail(&ss->workq_list, &sysfs_workq);
|
|
mutex_unlock(&sysfs_workq_mutex);
|
|
queue_work(sysfs_workqueue, &ss->work);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
|