c2b19daf67
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>
1182 lines
28 KiB
C
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);
|