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authorNeil Brown <neilb@suse.de>2008-07-16 08:58:04 +1000
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-16 09:24:47 -0700
commitf1282c844e86db5a041afa41335b5f9eea6cec0c (patch)
tree3736285f2f7ce145fb06538d616a9c1165ffc125 /fs/sysfs/file.c
parentec748fa9ed3fec44aeebbf86ae050b0cc7a978d9 (diff)
downloadvexpress-lsk-f1282c844e86db5a041afa41335b5f9eea6cec0c.tar.gz
sysfs: Support sysfs_notify from atomic context with new sysfs_notify_dirent
Support sysfs_notify from atomic context with new sysfs_notify_dirent sysfs_notify currently takes sysfs_mutex. This means that it cannot be called in atomic context. sysfs_mutex is sometimes held over a malloc (sysfs_rename_dir) so it can block on low memory. In md I want to be able to notify on a sysfs attribute from atomic context, and I don't want to block on low memory because I could be in the writeout path for freeing memory. So: - export the "sysfs_dirent" structure along with sysfs_get, sysfs_put and sysfs_get_dirent so I can get the sysfs_dirent that I want to notify on and hold it in an md structure. - split sysfs_notify_dirent out of sysfs_notify so the sysfs_dirent can be notified on with no blocking (just a spinlock). Signed-off-by: Neil Brown <neilb@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/sysfs/file.c')
-rw-r--r--fs/sysfs/file.c31
1 files changed, 18 insertions, 13 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index ce8339c70a4..d0d79e6b6d1 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -453,6 +453,22 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
return POLLERR|POLLPRI;
}
+void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+ 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);
+}
+EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
+
void sysfs_notify(struct kobject *k, char *dir, char *attr)
{
struct sysfs_dirent *sd = k->sd;
@@ -463,19 +479,8 @@ void sysfs_notify(struct kobject *k, char *dir, char *attr)
sd = sysfs_find_dirent(sd, dir);
if (sd && attr)
sd = sysfs_find_dirent(sd, attr);
- if (sd) {
- 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);
- }
+ if (sd)
+ sysfs_notify_dirent(sd);
mutex_unlock(&sysfs_mutex);
}