Hello Andrey Konovalov,
The patch f2c2e717642c: "usb: gadget: add raw-gadget interface" from
Feb 24, 2020, leads to the following static checker warning:
drivers/usb/gadget/legacy/raw_gadget.c:102 raw_event_queue_fetch() warn: inconsistent returns 'queue->sema'.
Locked on : 96,102
Unlocked on: 93
drivers/usb/gadget/legacy/raw_gadget.c
81 static struct usb_raw_event *raw_event_queue_fetch(
82 struct raw_event_queue *queue)
83 {
84 unsigned long flags;
85 struct usb_raw_event *event;
86
87 /*
88 * This function can be called concurrently. We first check that
89 * there's at least one event queued by decrementing the semaphore,
90 * and then take the lock to protect queue struct fields.
91 */
92 if (down_interruptible(&queue->sema))
93 return NULL;
94 spin_lock_irqsave(&queue->lock, flags);
95 if (WARN_ON(!queue->size))
96 return NULL;
I'm going to have investigate to see why Smatch doesn't complain that
we have disabled IRQs on this path... Anyway, this doesn't seem like it
can be correct. I get that this is a WARN_ON() path, but we're leaving
the computer in a very screwed up state we don't at least enable IRQs.
97 event = queue->events[0];
98 queue->size--;
99 memmove(&queue->events[0], &queue->events[1],
100 queue->size * sizeof(queue->events[0]));
101 spin_unlock_irqrestore(&queue->lock, flags);
102 return event;
103 }
regards,
dan carpenter
