#include <linux/fsnotify.h>
#include <linux/kobject.h>
#include <linux/namei.h>
+#include <linux/poll.h>
+#include <linux/limits.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>
struct sysfs_ops * ops;
struct semaphore sem;
int needs_read_fill;
+ int event;
};
*/
static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
{
+ struct sysfs_dirent * sd = dentry->d_fsdata;
struct attribute * attr = to_attr(dentry);
struct kobject * kobj = to_kobj(dentry->d_parent);
struct sysfs_ops * ops = buffer->ops;
if (!buffer->page)
return -ENOMEM;
+ buffer->event = atomic_read(&sd->s_event);
count = ops->show(kobj,attr,buffer->page);
buffer->needs_read_fill = 0;
BUG_ON(count > (ssize_t)PAGE_SIZE);
down(&buffer->sem);
if (buffer->needs_read_fill) {
- if ((retval = fill_read_buffer(file->f_dentry,buffer)))
+ if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
goto out;
}
- pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
- __FUNCTION__,count,*ppos,buffer->page);
+ pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
+ __FUNCTION__, count, *ppos, buffer->page);
retval = flush_read_buffer(buffer,buf,count,ppos);
out:
up(&buffer->sem);
count = PAGE_SIZE - 1;
error = copy_from_user(buffer->page,buf,count);
buffer->needs_read_fill = 1;
+ /* if buf is assumed to contain a string, terminate it by \0,
+ so e.g. sscanf() can scan the string easily */
+ buffer->page[count] = 0;
return error ? -EFAULT : count;
}
down(&buffer->sem);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
- len = flush_write_buffer(file->f_dentry, buffer, len);
+ len = flush_write_buffer(file->f_path.dentry, buffer, len);
if (len > 0)
*ppos += len;
up(&buffer->sem);
static int check_perm(struct inode * inode, struct file * file)
{
- struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
- struct attribute * attr = to_attr(file->f_dentry);
+ struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
+ struct attribute * attr = to_attr(file->f_path.dentry);
struct sysfs_buffer * buffer;
struct sysfs_ops * ops = NULL;
int error = 0;
/* No error? Great, allocate a buffer for the file, and store it
* it in file->private_data for easy access.
*/
- buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL);
+ buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
if (buffer) {
- memset(buffer,0,sizeof(struct sysfs_buffer));
init_MUTEX(&buffer->sem);
buffer->needs_read_fill = 1;
buffer->ops = ops;
return error;
}
+char last_sysfs_file[PATH_MAX];
+
static int sysfs_open_file(struct inode * inode, struct file * filp)
{
+ char *p = d_path(filp->f_dentry, sysfs_mount, last_sysfs_file,
+ sizeof(last_sysfs_file));
+ if (p)
+ memmove(last_sysfs_file, p, strlen(p) + 1);
return check_perm(inode,filp);
}
static int sysfs_release(struct inode * inode, struct file * filp)
{
- struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
- struct attribute * attr = to_attr(filp->f_dentry);
+ struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
+ struct attribute * attr = to_attr(filp->f_path.dentry);
struct module * owner = attr->owner;
struct sysfs_buffer * buffer = filp->private_data;
return 0;
}
-struct file_operations sysfs_file_operations = {
+/* 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, as simply seeking and reading
+ * again will not get new data, or reset the state of 'poll'.
+ * 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 (Nether 'poll' or '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_buffer * buffer = filp->private_data;
+ struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
+ struct sysfs_dirent * sd = filp->f_path.dentry->d_fsdata;
+ int res = 0;
+
+ poll_wait(filp, &kobj->poll, wait);
+
+ if (buffer->event != atomic_read(&sd->s_event)) {
+ res = POLLERR|POLLPRI;
+ buffer->needs_read_fill = 1;
+ }
+
+ return res;
+}
+
+
+static struct dentry *step_down(struct dentry *dir, const char * name)
+{
+ struct dentry * de;
+
+ if (dir == NULL || dir->d_inode == NULL)
+ return NULL;
+
+ mutex_lock(&dir->d_inode->i_mutex);
+ de = lookup_one_len(name, dir, strlen(name));
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(dir);
+ if (IS_ERR(de))
+ return NULL;
+ if (de->d_inode == NULL) {
+ dput(de);
+ return NULL;
+ }
+ return de;
+}
+
+void sysfs_notify(struct kobject * k, char *dir, char *attr)
+{
+ struct dentry *de = k->dentry;
+ if (de)
+ dget(de);
+ if (de && dir)
+ de = step_down(de, dir);
+ if (de && attr)
+ de = step_down(de, attr);
+ if (de) {
+ struct sysfs_dirent * sd = de->d_fsdata;
+ if (sd)
+ atomic_inc(&sd->s_event);
+ wake_up_interruptible(&k->poll);
+ dput(de);
+ }
+}
+EXPORT_SYMBOL_GPL(sysfs_notify);
+
+const struct file_operations sysfs_file_operations = {
.read = sysfs_read_file,
.write = sysfs_write_file,
.llseek = generic_file_llseek,
.open = sysfs_open_file,
.release = sysfs_release,
+ .poll = sysfs_poll,
};
{
struct sysfs_dirent * parent_sd = dir->d_fsdata;
umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
- int error = 0;
+ int error = -EEXIST;
mutex_lock(&dir->d_inode->i_mutex);
- error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+ if (!sysfs_dirent_exist(parent_sd, attr->name))
+ error = sysfs_make_dirent(parent_sd, NULL, (void *)attr,
+ mode, type);
mutex_unlock(&dir->d_inode->i_mutex);
return error;
d_drop(victim);
/**
- * Drop the reference acquired from sysfs_get_dentry() above.
+ * Drop the reference acquired from lookup_one_len() above.
*/
dput(victim);
}
git://git.onelab.eu / linux-2.6.git / blobdiff