diff options
| -rw-r--r-- | drivers/md/md.c | 1 | ||||
| -rw-r--r-- | fs/sysfs/dir.c | 1 | ||||
| -rw-r--r-- | fs/sysfs/file.c | 76 | ||||
| -rw-r--r-- | fs/sysfs/sysfs.h | 1 | ||||
| -rw-r--r-- | include/linux/kobject.h | 2 | ||||
| -rw-r--r-- | include/linux/sysfs.h | 6 | ||||
| -rw-r--r-- | lib/kobject.c | 1 |
7 files changed, 88 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 1ed5152db4506..434ca39d19c1d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -163,6 +163,7 @@ void md_new_event(mddev_t *mddev) { atomic_inc(&md_event_count); wake_up(&md_event_waiters); + sysfs_notify(&mddev->kobj, NULL, "sync_action"); } EXPORT_SYMBOL_GPL(md_new_event); diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 6cfdc9a87772b..610b5bdbe75bc 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; diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index f1cb1ddde511d..cf3786625bfad 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); @@ -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/sysfs.h b/fs/sysfs/sysfs.h index 32958a7c50e95..3651ffb5ec091 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 *); diff --git a/include/linux/kobject.h b/include/linux/kobject.h index 4cb1214ec2909..dcd0623be892f 100644 --- a/include/linux/kobject.h +++ b/include/linux/kobject.h @@ -24,6 +24,7 @@ #include <linux/rwsem.h> #include <linux/kref.h> #include <linux/kernel.h> +#include <linux/wait.h> #include <asm/atomic.h> #define KOBJ_NAME_LEN 20 @@ -56,6 +57,7 @@ struct kobject { struct kset * kset; struct kobj_type * ktype; struct dentry * dentry; + wait_queue_head_t poll; }; extern int kobject_set_name(struct kobject *, const char *, ...) diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index 392da5a6dacb7..1ea5d3cda6ae2 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -74,6 +74,7 @@ struct sysfs_dirent { umode_t s_mode; struct dentry * s_dentry; struct iattr * s_iattr; + atomic_t s_event; }; #define SYSFS_ROOT 0x0001 @@ -117,6 +118,7 @@ int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr); int sysfs_create_group(struct kobject *, const struct attribute_group *); void sysfs_remove_group(struct kobject *, const struct attribute_group *); +void sysfs_notify(struct kobject * k, char *dir, char *attr); #else /* CONFIG_SYSFS */ @@ -185,6 +187,10 @@ static inline void sysfs_remove_group(struct kobject * k, const struct attribute ; } +static inline void sysfs_notify(struct kobject * k, char *dir, char *attr) +{ +} + #endif /* CONFIG_SYSFS */ #endif /* _SYSFS_H_ */ diff --git a/lib/kobject.c b/lib/kobject.c index 25204a41a9b01..01d9575139408 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -128,6 +128,7 @@ void kobject_init(struct kobject * kobj) { kref_init(&kobj->kref); INIT_LIST_HEAD(&kobj->entry); + init_waitqueue_head(&kobj->poll); kobj->kset = kset_get(kobj->kset); } |