Hello Takashi Sakamoto,
The patch 634ec0b2906e: "ALSA: firewire-motu: notify event for
parameter change in register DSP model" from Oct 15, 2021, leads to
the following Smatch static checker warning:
sound/firewire/motu/motu-hwdep.c:92 hwdep_read()
warn: inconsistent returns '&motu->lock'.
sound/firewire/motu/motu-hwdep.c
27 static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
28 loff_t *offset)
29 {
30 struct snd_motu *motu = hwdep->private_data;
31 DEFINE_WAIT(wait);
32 union snd_firewire_event event;
33
34 spin_lock_irq(&motu->lock);
35
36 while (!motu->dev_lock_changed && motu->msg == 0 && !has_dsp_event(motu)) {
37 prepare_to_wait(&motu->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
38 spin_unlock_irq(&motu->lock);
39 schedule();
40 finish_wait(&motu->hwdep_wait, &wait);
41 if (signal_pending(current))
42 return -ERESTARTSYS;
43 spin_lock_irq(&motu->lock);
44 }
45
46 memset(&event, 0, sizeof(event));
47 if (motu->dev_lock_changed) {
48 event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
49 event.lock_status.status = (motu->dev_lock_count > 0);
50 motu->dev_lock_changed = false;
51 spin_unlock_irq(&motu->lock);
52
53 count = min_t(long, count, sizeof(event));
54 if (copy_to_user(buf, &event, count))
55 return -EFAULT;
56 } else if (motu->msg > 0) {
57 event.motu_notification.type = SNDRV_FIREWIRE_EVENT_MOTU_NOTIFICATION;
58 event.motu_notification.message = motu->msg;
59 motu->msg = 0;
60 spin_unlock_irq(&motu->lock);
61
62 count = min_t(long, count, sizeof(event));
63 if (copy_to_user(buf, &event, count))
64 return -EFAULT;
65 } else if (has_dsp_event(motu)) {
66 size_t consumed = 0;
67 u32 __user *ptr;
68 u32 ev;
69
70 spin_unlock_irq(&motu->lock);
71
72 // Header is filled later.
73 consumed += sizeof(event.motu_register_dsp_change);
74
75 while (consumed < count &&
76 snd_motu_register_dsp_message_parser_copy_event(motu, &ev)) {
77 ptr = (u32 __user *)(buf + consumed);
78 if (put_user(ev, ptr))
79 return -EFAULT;
80 consumed += sizeof(ev);
81 }
82
83 event.motu_register_dsp_change.type = SNDRV_FIREWIRE_EVENT_MOTU_REGISTER_DSP_CHANGE;
84 event.motu_register_dsp_change.count =
85 (consumed - sizeof(event.motu_register_dsp_change)) / 4;
86 if (copy_to_user(buf, &event, sizeof(event.motu_register_dsp_change)))
87 return -EFAULT;
88
89 count = consumed;
90 }
Smatch complains that there is no "} else {" path which unlocks.
91
--> 92 return count;
93 }
regards,
dan carpenter
