diff options
Diffstat (limited to 'fs/sysfs')
| -rw-r--r-- | fs/sysfs/dir.c | 3 | ||||
| -rw-r--r-- | fs/sysfs/file.c | 78 | ||||
| -rw-r--r-- | fs/sysfs/inode.c | 3 | ||||
| -rw-r--r-- | fs/sysfs/sysfs.h | 1 |
4 files changed, 81 insertions, 4 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index f26880a4785..610b5bdbe75 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -43,6 +43,7 @@ static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd, memset(sd, 0, sizeof(*sd)); atomic_set(&sd->s_count, 1); + atomic_set(&sd->s_event, 0); INIT_LIST_HEAD(&sd->s_children); list_add(&sd->s_sibling, &parent_sd->s_children); sd->s_element = element; @@ -50,7 +51,7 @@ static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd, return sd; } -/** +/* * * Return -EEXIST if there is already a sysfs element with the same name for * the same parent. diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 830f76fa098..cf3786625bf 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -6,6 +6,7 @@ #include <linux/fsnotify.h> #include <linux/kobject.h> #include <linux/namei.h> +#include <linux/poll.h> #include <asm/uaccess.h> #include <asm/semaphore.h> @@ -57,6 +58,7 @@ struct sysfs_buffer { struct sysfs_ops * ops; struct semaphore sem; int needs_read_fill; + int event; }; @@ -72,6 +74,7 @@ struct sysfs_buffer { */ 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; @@ -83,6 +86,7 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer 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); @@ -183,7 +187,7 @@ fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t return -ENOMEM; if (count >= PAGE_SIZE) - count = PAGE_SIZE; + count = PAGE_SIZE - 1; error = copy_from_user(buffer->page,buf,count); buffer->needs_read_fill = 1; return error ? -EFAULT : count; @@ -348,12 +352,84 @@ static int sysfs_release(struct inode * inode, struct file * filp) return 0; } +/* 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_dentry->d_parent); + struct sysfs_dirent * sd = filp->f_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, }; diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 4c29ac41ac3..f0b347bd12c 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -175,8 +175,7 @@ const unsigned char * sysfs_get_name(struct sysfs_dirent *sd) struct bin_attribute * bin_attr; struct sysfs_symlink * sl; - if (!sd || !sd->s_element) - BUG(); + BUG_ON(!sd || !sd->s_element); switch (sd->s_type) { case SYSFS_DIR: diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 32958a7c50e..3651ffb5ec0 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -11,6 +11,7 @@ extern int sysfs_make_dirent(struct sysfs_dirent *, struct dentry *, void *, extern int sysfs_add_file(struct dentry *, const struct attribute *, int); extern void sysfs_hash_and_remove(struct dentry * dir, const char * name); +extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name); extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **); extern void sysfs_remove_subdir(struct dentry *); |