tmp_suning_uos_patched/fs/sysfs/file.c
Tejun Heo c2b19daf67 sysfs, kernfs: prepare read path for kernfs
We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges read path so that the kernfs and sysfs parts are separate.

* Regular file read path is refactored such that
  kernfs_seq_start/next/stop/show() handle all the boilerplate work
  including locking and updating event count for poll, while
  sysfs_kf_seq_show() deals with interaction with kobj show method.

* Bin file read path is refactored such that kernfs_file_direct_read()
  handles all the boilerplate work including buffer management and
  locking, while sysfs_kf_bin_read() deals with interaction with
  bin_attribute read method.

kernfs_file_read() is added.  It invokes either the seq_file or direct
read path depending on the file type.  This will eventually allow
using the same file_operations for both file types, which is necessary
to separate out kernfs.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show().
    Add comments explaining single_open() behavior.  Both suggested by
    Pavel.

v3: seq_stop() is called even after seq_start() failed.
    kernfs_seq_start() updated so that it doesn't unlock
    sysfs_open_file->mutex on failure so that kernfs_seq_stop()
    doesn't try to unlock an already unlocked mutex.  Reported by
    Fengguang.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 17:33:46 -08:00

1182 lines
28 KiB
C

/*
* fs/sysfs/file.c - sysfs regular (text) file implementation
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/kallsyms.h>
#include <linux/slab.h>
#include <linux/fsnotify.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/limits.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/mm.h>
#include "sysfs.h"
/*
* There's one sysfs_open_file for each open file and one sysfs_open_dirent
* for each sysfs_dirent with one or more open files.
*
* sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open is
* protected by sysfs_open_dirent_lock.
*
* filp->private_data points to seq_file whose ->private points to
* sysfs_open_file. sysfs_open_files are chained at
* sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
*/
static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
static DEFINE_MUTEX(sysfs_open_file_mutex);
struct sysfs_open_dirent {
atomic_t refcnt;
atomic_t event;
wait_queue_head_t poll;
struct list_head files; /* goes through sysfs_open_file.list */
};
struct sysfs_open_file {
struct sysfs_dirent *sd;
struct file *file;
struct mutex mutex;
int event;
struct list_head list;
bool mmapped;
const struct vm_operations_struct *vm_ops;
};
static bool sysfs_is_bin(struct sysfs_dirent *sd)
{
return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
}
static struct sysfs_open_file *sysfs_of(struct file *file)
{
return ((struct seq_file *)file->private_data)->private;
}
/*
* Determine ktype->sysfs_ops for the given sysfs_dirent. This function
* must be called while holding an active reference.
*/
static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
{
struct kobject *kobj = sd->s_parent->priv;
if (!sysfs_ignore_lockdep(sd))
lockdep_assert_held(sd);
return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
}
/*
* Reads on sysfs are handled through seq_file, which takes care of hairy
* details like buffering and seeking. The following function pipes
* sysfs_ops->show() result through seq_file.
*/
static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
struct kobject *kobj = of->sd->s_parent->priv;
const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
ssize_t count;
char *buf;
/* acquire buffer and ensure that it's >= PAGE_SIZE */
count = seq_get_buf(sf, &buf);
if (count < PAGE_SIZE) {
seq_commit(sf, -1);
return 0;
}
/*
* Invoke show(). Control may reach here via seq file lseek even
* if @ops->show() isn't implemented.
*/
if (ops->show) {
count = ops->show(kobj, of->sd->priv, buf);
if (count < 0)
return count;
}
/*
* The code works fine with PAGE_SIZE return but it's likely to
* indicate truncated result or overflow in normal use cases.
*/
if (count >= (ssize_t)PAGE_SIZE) {
print_symbol("fill_read_buffer: %s returned bad count\n",
(unsigned long)ops->show);
/* Try to struggle along */
count = PAGE_SIZE - 1;
}
seq_commit(sf, count);
return 0;
}
static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->sd->priv;
struct kobject *kobj = of->sd->s_parent->priv;
loff_t size = file_inode(of->file)->i_size;
if (!count)
return 0;
if (size) {
if (pos > size)
return 0;
if (pos + count > size)
count = size - pos;
}
if (!battr->read)
return -EIO;
return battr->read(of->file, kobj, battr, buf, pos, count);
}
static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd))
return ERR_PTR(-ENODEV);
/*
* The same behavior and code as single_open(). Returns !NULL if
* pos is at the beginning; otherwise, NULL.
*/
return NULL + !*ppos;
}
static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
{
/*
* The same behavior and code as single_open(), always terminate
* after the initial read.
*/
++*ppos;
return NULL;
}
static void kernfs_seq_stop(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
}
static int kernfs_seq_show(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
of->event = atomic_read(&of->sd->s_attr.open->event);
return sysfs_kf_seq_show(sf, v);
}
static const struct seq_operations kernfs_seq_ops = {
.start = kernfs_seq_start,
.next = kernfs_seq_next,
.stop = kernfs_seq_stop,
.show = kernfs_seq_show,
};
/*
* As reading a bin file can have side-effects, the exact offset and bytes
* specified in read(2) call should be passed to the read callback making
* it difficult to use seq_file. Implement simplistic custom buffering for
* bin files.
*/
static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
char __user *user_buf, size_t count,
loff_t *ppos)
{
ssize_t len = min_t(size_t, count, PAGE_SIZE);
char *buf;
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
len = -ENODEV;
mutex_unlock(&of->mutex);
goto out_free;
}
len = sysfs_kf_bin_read(of, buf, len, *ppos);
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len < 0)
goto out_free;
if (copy_to_user(user_buf, buf, len)) {
len = -EFAULT;
goto out_free;
}
*ppos += len;
out_free:
kfree(buf);
return len;
}
/**
* kernfs_file_read - kernfs vfs read callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*/
static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
if (sysfs_is_bin(of->sd))
return kernfs_file_direct_read(of, user_buf, count, ppos);
else
return seq_read(file, user_buf, count, ppos);
}
/**
* flush_write_buffer - push buffer to kobject
* @of: open file
* @buf: data buffer for file
* @off: file offset to write to
* @count: number of bytes
*
* Get the correct pointers for the kobject and the attribute we're dealing
* with, then call the store() method for it with @buf.
*/
static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
size_t count)
{
struct kobject *kobj = of->sd->s_parent->priv;
int rc = 0;
/*
* Need @of->sd for attr and ops, its parent for kobj. @of->mutex
* nests outside active ref and is just to ensure that the ops
* aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
mutex_unlock(&of->mutex);
return -ENODEV;
}
if (sysfs_is_bin(of->sd)) {
struct bin_attribute *battr = of->sd->priv;
rc = -EIO;
if (battr->write)
rc = battr->write(of->file, kobj, battr, buf, off,
count);
} else {
const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
rc = ops->store(kobj, of->sd->priv, buf, count);
}
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
return rc;
}
/**
* sysfs_write_file - write an attribute
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Copy data in from userland and pass it to the matching
* sysfs_ops->store() by invoking 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 *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
ssize_t len = min_t(size_t, count, PAGE_SIZE);
loff_t size = file_inode(file)->i_size;
char *buf;
if (sysfs_is_bin(of->sd) && size) {
if (size <= *ppos)
return 0;
len = min_t(ssize_t, len, size - *ppos);
}
if (!len)
return 0;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, len)) {
len = -EFAULT;
goto out_free;
}
buf[len] = '\0'; /* guarantee string termination */
len = flush_write_buffer(of, buf, *ppos, len);
if (len > 0)
*ppos += len;
out_free:
kfree(buf);
return len;
}
static void sysfs_bin_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
if (!of->vm_ops)
return;
if (!sysfs_get_active(of->sd))
return;
if (of->vm_ops->open)
of->vm_ops->open(vma);
sysfs_put_active(of->sd);
}
static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
if (of->vm_ops->fault)
ret = of->vm_ops->fault(vma, vmf);
sysfs_put_active(of->sd);
return ret;
}
static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = 0;
if (of->vm_ops->page_mkwrite)
ret = of->vm_ops->page_mkwrite(vma, vmf);
else
file_update_time(file);
sysfs_put_active(of->sd);
return ret;
}
static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return -EINVAL;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = -EINVAL;
if (of->vm_ops->access)
ret = of->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(of->sd);
return ret;
}
#ifdef CONFIG_NUMA
static int sysfs_bin_set_policy(struct vm_area_struct *vma,
struct mempolicy *new)
{
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 -EINVAL;
ret = 0;
if (of->vm_ops->set_policy)
ret = of->vm_ops->set_policy(vma, new);
sysfs_put_active(of->sd);
return ret;
}
static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
struct mempolicy *pol;
if (!of->vm_ops)
return vma->vm_policy;
if (!sysfs_get_active(of->sd))
return vma->vm_policy;
pol = vma->vm_policy;
if (of->vm_ops->get_policy)
pol = of->vm_ops->get_policy(vma, addr);
sysfs_put_active(of->sd);
return pol;
}
static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
const nodemask_t *to, unsigned long flags)
{
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)
ret = of->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active(of->sd);
return ret;
}
#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->priv;
struct kobject *kobj = of->sd->s_parent->priv;
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->priv;
struct sysfs_open_file *of;
bool has_read, has_write, has_mmap;
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->priv;
has_read = battr->read || battr->mmap;
has_write = battr->write || battr->mmap;
has_mmap = 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;
has_mmap = false;
}
/* 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;
/*
* The following is done to give a different lockdep key to
* @of->mutex for files which implement mmap. This is a rather
* crude way to avoid false positive lockdep warning around
* mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
* reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
* which mm->mmap_sem nests, while holding @of->mutex. As each
* open file has a separate mutex, it's okay as long as those don't
* happen on the same file. At this point, we can't easily give
* each file a separate locking class. Let's differentiate on
* whether the file has mmap or not for now.
*/
if (has_mmap)
mutex_init(&of->mutex);
else
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 = seq_open(file, NULL);
else
error = seq_open(file, &kernfs_seq_ops);
if (error)
goto err_free;
((struct seq_file *)file->private_data)->private = of;
/* 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:
seq_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);
seq_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 = kernfs_file_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 = kernfs_file_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->priv = (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;
sd = sysfs_get_dirent(kobj->sd, attr->name);
if (!sd)
return -ENOENT;
newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE;
rc = kernfs_setattr(sd, &newattrs);
sysfs_put(sd);
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;
kernfs_remove_by_name_ns(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) {
kernfs_remove_by_name(dir_sd, attr->name);
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)
{
kernfs_remove_by_name(kobj->sd, attr->attr.name);
}
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);