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vt: synchronize_rcu() under spinlock is not nice... 

vcs_poll_data_free() calls unregister_vt_notifier(), which calls
atomic_notifier_chain_unregister(), which calls synchronize_rcu().
Do it *after* we'd dropped ->f_lock.

Cc: stable@vger.kernel.org (all kernels since 2.6.37)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-03-26 20:30:17 -04:00
parent 7ea600b531
commit e8cd81693b
1 changed files with 4 additions and 2 deletions
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6
drivers/tty/vt/vc_screen.c
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@ -93,7 +93,7 @@ vcs_poll_data_free(struct vcs_poll_data *poll)
static struct vcs_poll_data *
vcs_poll_data_get(struct file *file)
{
struct vcs_poll_data *poll = file->private_data;
struct vcs_poll_data *poll = file->private_data, *kill = NULL;
if (poll)
return poll;
@ -122,10 +122,12 @@ vcs_poll_data_get(struct file *file)
file->private_data = poll;
} else {
/* someone else raced ahead of us */
vcs_poll_data_free(poll);
kill = poll;
poll = file->private_data;
}
spin_unlock(&file->f_lock);
if (kill)
vcs_poll_data_free(kill);
return poll;
}