fix error return code

The complate semantic patch that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@ok exists@
identifier f,ret,i;
expression e;
constant c;
@@

// identify a function that returns a negative return value at least once.
f(...) {
... when any
(
return -c@i;
|
ret = -c@i;
... when != ret = e
return ret;
|
if (ret < 0) { ... return ret; }
)
... when any
}

@r exists@
identifier ret,ok.f,fn;
expression e1,e2,e3,e4,e5,e6,x;
statement S,S1;
position p1,p2,p3;
@@

// identify a case where the return variable is set to a non-negative value
// and then returned in error-handling code
f(...) {
... when any
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|

115 more lines

Propagate error code on failure.  Also changed %ld to %d in dev_err to use
ret variable rather than putting two calls to PTR_ERR.

A simplified version of the semantic match that finds the first problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier ret; expression e1,e2;
@@
(
if (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}
// </smpl>

Signed-off-by: Julia Lawall <redacted>

---
 drivers/video/fbdev/ssd1307fb.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 3e153c0..1611215 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c

@@ -656,8 +656,9 @@ static int ssd1307fb_probe(struct i2c_client *client,
 	bl = backlight_device_register(bl_name, &client->dev, par,
 				       &ssd1307fb_bl_ops, NULL);
 	if (IS_ERR(bl)) {
-		dev_err(&client->dev, "unable to register backlight device: %ld\n",
-			PTR_ERR(bl));
+		ret = PTR_ERR(bl);
+		dev_err(&client->dev, "unable to register backlight device: %d\n",
+			ret);
 		goto bl_init_error;
 	}
 

On 23/08/15 03:11, Julia Lawall wrote:

7 more quoted lines

Thanks, queued for 4.3.

 Tomi