drivers/rtc: correct error-handling code
Julia Lawall [Tue, 22 Sep 2009 23:46:29 +0000 (16:46 -0700)]
This code is not executed before ds1307->rtc has been successfully
initialized to the result of calling rtc_device_register.  Thus the test
that ds1307->rtc is not NULL is always true.

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

// <smpl>
@match exists@
expression x, E;
statement S1, S2;
@@

x = rtc_device_register(...)
... when != x = E
(
*  if (x == NULL || ...) S1 else S2
|
*  if (x == NULL && ...) S1 else S2
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-ds1307.c

index 47a93c0..eb99ee4 100644 (file)
@@ -896,8 +896,7 @@ read_rtc:
        return 0;
 
 exit_irq:
-       if (ds1307->rtc)
-               rtc_device_unregister(ds1307->rtc);
+       rtc_device_unregister(ds1307->rtc);
 exit_free:
        kfree(ds1307);
        return err;