Allow uvideo_mmap_queue() to fail gracefully when the mmap queue is full;

found the hard way by sebastia@ four years ago, and I'd been sitting on that
diff since.

The initial diff was more aggressive and would free the mmap queue upon error,
but jakemsr@ had objections against this behaviour; this diff only fails
gracefully instead of panic'ing.

diff --git a/sys/dev/usb/uvideo.c b/sys/dev/usb/uvideo.c
index 4d90f5b..06ae1d5 100644 (file)
--- a/sys/dev/usb/uvideo.c
+++ b/sys/dev/usb/uvideo.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uvideo.c,v 1.179 2015/01/06 17:27:58 armani Exp $ */
+/*     $OpenBSD: uvideo.c,v 1.180 2015/06/24 20:17:28 miod Exp $ */
 
 /*
  * Copyright (c) 2008 Robert Nagy <robert@openbsd.org>
@@ -122,7 +122,7 @@ usbd_status uvideo_vs_decode_stream_header(struct uvideo_softc *,
                    uint8_t *, int); 
 usbd_status    uvideo_vs_decode_stream_header_isight(struct uvideo_softc *,
                    uint8_t *, int);
-void           uvideo_mmap_queue(struct uvideo_softc *, uint8_t *, int);
+int            uvideo_mmap_queue(struct uvideo_softc *, uint8_t *, int);
 void           uvideo_read(struct uvideo_softc *, uint8_t *, int);
 usbd_status    uvideo_usb_control(struct uvideo_softc *sc, uint8_t rt, uint8_t r,
                    uint16_t value, uint8_t *data, size_t length);
@@ -2076,7 +2076,8 @@ uvideo_vs_decode_stream_header(struct uvideo_softc *sc, uint8_t *frame,
 #endif
                        if (sc->sc_mmap_flag) {
                                /* mmap */
-                               uvideo_mmap_queue(sc, fb->buf, fb->offset);
+                               if (uvideo_mmap_queue(sc, fb->buf, fb->offset))
+                                       return (USBD_NOMEM);
                        } else {
                                /* read */
                                uvideo_read(sc, fb->buf, fb->offset);
@@ -2129,7 +2130,8 @@ uvideo_vs_decode_stream_header_isight(struct uvideo_softc *sc, uint8_t *frame,
        if (header) {
                if (sc->sc_mmap_flag) {
                        /* mmap */
-                       uvideo_mmap_queue(sc, fb->buf, fb->offset);
+                       if (uvideo_mmap_queue(sc, fb->buf, fb->offset))
+                               return (USBD_NOMEM);
                } else {
                        /* read */
                        uvideo_read(sc, fb->buf, fb->offset);
@@ -2147,7 +2149,7 @@ uvideo_vs_decode_stream_header_isight(struct uvideo_softc *sc, uint8_t *frame,
        return (USBD_NORMAL_COMPLETION);
 }
 
-void
+int
 uvideo_mmap_queue(struct uvideo_softc *sc, uint8_t *buf, int len)
 {
        if (sc->sc_mmap_cur < 0 || sc->sc_mmap_count == 0 ||
@@ -2162,8 +2164,11 @@ uvideo_mmap_queue(struct uvideo_softc *sc, uint8_t *buf, int len)
                /* not ready for queueing, try next */
                sc->sc_mmap_cur++;
        }
-       if (sc->sc_mmap_cur == sc->sc_mmap_count)
-               panic("uvideo_mmap_queue: mmap queue is full!");
+       if (sc->sc_mmap_cur == sc->sc_mmap_count) {
+               DPRINTF(1, "%s: %s: mmap queue is full!",
+                   DEVNAME(sc), __func__);
+               return ENOMEM;
+       }
 
        /* copy frame to mmap buffer and report length */
        bcopy(buf, sc->sc_mmap[sc->sc_mmap_cur].buf, len);
@@ -2191,6 +2196,8 @@ uvideo_mmap_queue(struct uvideo_softc *sc, uint8_t *buf, int len)
         * ready to dequeue.
         */
        sc->sc_uplayer_intr(sc->sc_uplayer_arg);
+
+       return 0;
 }
 
 void
@@ -3096,7 +3103,8 @@ uvideo_reqbufs(void *v, struct v4l2_requestbuffers *rb)
                return (EINVAL);
 
        if (sc->sc_mmap_count > 0 || sc->sc_mmap_buffer != NULL) {
-               printf("%s: mmap buffers already allocated\n", __func__);
+               DPRINTF(1, "%s: %s: mmap buffers already allocated\n",
+                   DEVNAME(sc), __func__);
                return (EINVAL);
        }