From: Al Viro Date: Wed, 27 Mar 2013 00:30:17 +0000 (-0400) Subject: vt: synchronize_rcu() under spinlock is not nice... X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e8cd81693bbbb15db57d3c9aa7dd90eda4842874;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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 --- diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index e4ca345873c3..d7799deacb21 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; }