From a4e8b912541d5372ae049a3b7c1979968e52c40b Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 20 Sep 2007 16:05:12 +0900 Subject: sysfs: move sysfs file poll implementation to sysfs_open_dirent Sysfs file poll implementation is scattered over sysfs and kobject. Event numbering is done in sysfs_dirent but wait itself is done on kobject. This not only unecessarily bloats both kobject and sysfs_dirent but is also buggy - if a sysfs_dirent is removed while there still are pollers, the associaton betwen the kobject and sysfs_dirent breaks and kobject may be freed with the pollers still sleeping on it. This patch moves whole poll implementation into sysfs_open_dirent. Each time a sysfs_open_dirent is created, event number restarts from 1 and pollers sleep on sysfs_open_dirent. As event sequence number is meaningless without any open file and pollers should have open file and thus sysfs_open_dirent, this ephemeral event counting works and is a saner implementation. This patch fixes the dnagling sleepers bug and reduces the sizes of kobject and sysfs_dirent by one pointer. Signed-off-by: Tejun Heo Acked-by: Cornelia Huck Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/file.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) (limited to 'fs/sysfs/file.c') diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index b13ba94cf8ac..c05f9618b2dc 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -62,6 +62,8 @@ static spinlock_t sysfs_open_dirent_lock = SPIN_LOCK_UNLOCKED; struct sysfs_open_dirent { atomic_t refcnt; + atomic_t event; + wait_queue_head_t poll; struct list_head buffers; /* goes through sysfs_buffer.list */ }; @@ -104,7 +106,7 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer if (!sysfs_get_active_two(attr_sd)) return -ENODEV; - buffer->event = atomic_read(&attr_sd->s_event); + buffer->event = atomic_read(&attr_sd->s_attr.open->event); count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page); sysfs_put_active_two(attr_sd); @@ -301,6 +303,8 @@ static int sysfs_get_open_dirent(struct sysfs_dirent *sd, 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->buffers); goto retry; } @@ -443,17 +447,17 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait) { struct sysfs_buffer * buffer = filp->private_data; struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata; - struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; + struct sysfs_open_dirent *od = attr_sd->s_attr.open; /* need parent for the kobj, grab both */ if (!sysfs_get_active_two(attr_sd)) goto trigger; - poll_wait(filp, &kobj->poll, wait); + poll_wait(filp, &od->poll, wait); sysfs_put_active_two(attr_sd); - if (buffer->event != atomic_read(&attr_sd->s_event)) + if (buffer->event != atomic_read(&od->event)) goto trigger; return 0; @@ -474,8 +478,17 @@ void sysfs_notify(struct kobject *k, char *dir, char *attr) if (sd && attr) sd = sysfs_find_dirent(sd, attr); if (sd) { - atomic_inc(&sd->s_event); - wake_up_interruptible(&k->poll); + struct sysfs_open_dirent *od; + + spin_lock(&sysfs_open_dirent_lock); + + od = sd->s_attr.open; + if (od) { + atomic_inc(&od->event); + wake_up_interruptible(&od->poll); + } + + spin_unlock(&sysfs_open_dirent_lock); } mutex_unlock(&sysfs_mutex); -- cgit v1.2.3