staging/olpc_docn: reorder the lock sequence to avoid potential dead lock

The lock sequence of dcon_blank_fb(fb_info->lock ---> console_lock) is against
with the one of console_callback(console_lock ---> fb_info->lock), it'll
lead to a potential dead lock, so reorder the lock sequence of dcon_blank_fb
to avoid the potential dead lock.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index 92b0289..26b4ec5 100644 (file)
--- a/drivers/staging/olpc_dcon/olpc_dcon.c
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -255,17 +255,19 @@ static bool dcon_blank_fb(struct dcon_priv *dcon, bool blank)
 {
        int err;
 
+       console_lock();
        if (!lock_fb_info(dcon->fbinfo)) {
+               console_unlock();
                dev_err(&dcon->client->dev, "unable to lock framebuffer\n");
                return false;
        }
-       console_lock();
+
        dcon->ignore_fb_events = true;
        err = fb_blank(dcon->fbinfo,
                        blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK);
        dcon->ignore_fb_events = false;
-       console_unlock();
        unlock_fb_info(dcon->fbinfo);
+       console_unlock();
 
        if (err) {
                dev_err(&dcon->client->dev, "couldn't %sblank framebuffer\n",