don't bother with vfsmount_lock in mounts_poll()
wake_up_interruptible/poll_wait provide sufficient barriers; just use ACCESS_ONCE() to fetch ns->event and that's it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -20,15 +20,15 @@ static unsigned mounts_poll(struct file *file, poll_table *wait)
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struct proc_mounts *p = proc_mounts(file->private_data);
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struct mnt_namespace *ns = p->ns;
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unsigned res = POLLIN | POLLRDNORM;
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int event;
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poll_wait(file, &p->ns->poll, wait);
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br_read_lock(&vfsmount_lock);
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if (p->m.poll_event != ns->event) {
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p->m.poll_event = ns->event;
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event = ACCESS_ONCE(ns->event);
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if (p->m.poll_event != event) {
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p->m.poll_event = event;
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res |= POLLERR | POLLPRI;
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}
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br_read_unlock(&vfsmount_lock);
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return res;
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}
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