[RESEND PATCH 2/2] staging/olpc_docn: reorder the lock sequence to avoid potential dead lock

Gu Zheng
2013-11-05T10:07:13Z

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>
---
drivers/staging/olpc_dcon/olpc_dcon.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index 198595e..9db88d9 100644
--- 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",
--
1.7.7