ALSA: sound/parisc: Move dereference after NULL test

If the NULL test on h is needed in snd_harmony_mixer_init, then the
dereference should be after the NULL test.

Actually, there is a sequence of calls: snd_harmony_create, then
snd_harmony_pcm_init, and then snd_harmony_mixer_init.  snd_harmony_create
initializes h, but may indeed leave it as NULL.  There was no NULL test at
the beginning of snd_harmony_pcm_init, so I have added one.  The NULL test
in snd_harmony_mixer_init is then not necessary, but in case the ordering
of the calls changes, I have left it, and moved the dereference after it.

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

// <smpl>
@match exists@
expression x, E;
identifier fld;
@@

* x->fld
  ... when != \(x = E\|&x\)
* x == NULL
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/parisc/harmony.c b/sound/parisc/harmony.c
index e924492..f47f9e2 100644 (file)
--- a/sound/parisc/harmony.c
+++ b/sound/parisc/harmony.c
@@ -624,6 +624,9 @@ snd_harmony_pcm_init(struct snd_harmony *h)
        struct snd_pcm *pcm;
        int err;
 
+       if (snd_BUG_ON(!h))
+               return -EINVAL;
+
        harmony_disable_interrupts(h);
        
        err = snd_pcm_new(h->card, "harmony", 0, 1, 1, &pcm);
@@ -865,11 +868,12 @@ snd_harmony_mixer_reset(struct snd_harmony *h)
 static int __devinit
 snd_harmony_mixer_init(struct snd_harmony *h)
 {
-       struct snd_card *card = h->card;
+       struct snd_card *card;
        int idx, err;
 
        if (snd_BUG_ON(!h))
                return -EINVAL;
+       card = h->card;
        strcpy(card->mixername, "Harmony Gain control interface");
 
        for (idx = 0; idx < HARMONY_CONTROLS; idx++) {