| From | Luis Henriques <> | Subject | [PATCH 014/102] vt: synchronize_rcu() under spinlock is not nice... | Date | Mon, 8 Apr 2013 10:49:29 +0100 |
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3.5.7.10 -stable review patch. If anyone has any objections, please let me know.
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From: Al Viro <viro@zeniv.linux.org.uk>
commit e8cd81693bbbb15db57d3c9aa7dd90eda4842874 upstream.
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.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/tty/vt/vc_screen.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index fa7268a..6abb92c 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -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; } -- 1.8.1.2
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