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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-04 03:53:13 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-04 03:53:13 +0200 |
commit | 3089f54a7928d28645661c2f3d829e3939d60dd3 (patch) | |
tree | 5709fd26998109924da0f2e27154413980b201af /fs | |
parent | Merge tag 'trace-fixes-v3.16-rc3' of git://git.kernel.org/pub/scm/linux/kerne... (diff) | |
parent | lz4: add overrun checks to lz4_uncompress_unknownoutputsize() (diff) | |
download | linux-3089f54a7928d28645661c2f3d829e3939d60dd3.tar.xz linux-3089f54a7928d28645661c2f3d829e3939d60dd3.zip |
Merge tag 'driver-core-3.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core fixes from Greg KH:
"Well, one drivercore fix for kernfs to resolve a reported issue with
sysfs files being updated from atomic contexts, and another lz4 bugfix
for testing potential buffer overflows"
* tag 'driver-core-3.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
lz4: add overrun checks to lz4_uncompress_unknownoutputsize()
kernfs: kernfs_notify() must be useable from non-sleepable contexts
Diffstat (limited to 'fs')
-rw-r--r-- | fs/kernfs/file.c | 69 |
1 files changed, 55 insertions, 14 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index e3d37f607f97..d895b4b7b661 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -39,6 +39,19 @@ struct kernfs_open_node { struct list_head files; /* goes through kernfs_open_file.list */ }; +/* + * kernfs_notify() may be called from any context and bounces notifications + * through a work item. To minimize space overhead in kernfs_node, the + * pending queue is implemented as a singly linked list of kernfs_nodes. + * The list is terminated with the self pointer so that whether a + * kernfs_node is on the list or not can be determined by testing the next + * pointer for NULL. + */ +#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list) + +static DEFINE_SPINLOCK(kernfs_notify_lock); +static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL; + static struct kernfs_open_file *kernfs_of(struct file *file) { return ((struct seq_file *)file->private_data)->private; @@ -783,24 +796,25 @@ static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait) return DEFAULT_POLLMASK|POLLERR|POLLPRI; } -/** - * kernfs_notify - notify a kernfs file - * @kn: file to notify - * - * Notify @kn such that poll(2) on @kn wakes up. - */ -void kernfs_notify(struct kernfs_node *kn) +static void kernfs_notify_workfn(struct work_struct *work) { - struct kernfs_root *root = kernfs_root(kn); + struct kernfs_node *kn; struct kernfs_open_node *on; struct kernfs_super_info *info; - unsigned long flags; - - if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) +repeat: + /* pop one off the notify_list */ + spin_lock_irq(&kernfs_notify_lock); + kn = kernfs_notify_list; + if (kn == KERNFS_NOTIFY_EOL) { + spin_unlock_irq(&kernfs_notify_lock); return; + } + kernfs_notify_list = kn->attr.notify_next; + kn->attr.notify_next = NULL; + spin_unlock_irq(&kernfs_notify_lock); /* kick poll */ - spin_lock_irqsave(&kernfs_open_node_lock, flags); + spin_lock_irq(&kernfs_open_node_lock); on = kn->attr.open; if (on) { @@ -808,12 +822,12 @@ void kernfs_notify(struct kernfs_node *kn) wake_up_interruptible(&on->poll); } - spin_unlock_irqrestore(&kernfs_open_node_lock, flags); + spin_unlock_irq(&kernfs_open_node_lock); /* kick fsnotify */ mutex_lock(&kernfs_mutex); - list_for_each_entry(info, &root->supers, node) { + list_for_each_entry(info, &kernfs_root(kn)->supers, node) { struct inode *inode; struct dentry *dentry; @@ -833,6 +847,33 @@ void kernfs_notify(struct kernfs_node *kn) } mutex_unlock(&kernfs_mutex); + kernfs_put(kn); + goto repeat; +} + +/** + * kernfs_notify - notify a kernfs file + * @kn: file to notify + * + * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any + * context. + */ +void kernfs_notify(struct kernfs_node *kn) +{ + static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn); + unsigned long flags; + + if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) + return; + + spin_lock_irqsave(&kernfs_notify_lock, flags); + if (!kn->attr.notify_next) { + kernfs_get(kn); + kn->attr.notify_next = kernfs_notify_list; + kernfs_notify_list = kn; + schedule_work(&kernfs_notify_work); + } + spin_unlock_irqrestore(&kernfs_notify_lock, flags); } EXPORT_SYMBOL_GPL(kernfs_notify); |