sniffer: only allocate USB message if queue is not too long

When the host does not retrieved the USB messages, they keep getting
queue in the firmware, filling the RAM, and preventing further memory
to be allocated.

Change-Id: I0e447acdf757dcb5dc5c4d8b84a4235866914cad

1 files changed, 8 insertions, 0 deletions

diff --git a/firmware/libcommon/source/sniffer.c b/firmware/libcommon/source/sniffer.c
index 1c691af..0ca71a5 100644
--- a/firmware/libcommon/source/sniffer.c
+++ b/firmware/libcommon/source/sniffer.c
@@ -226,6 +226,14 @@ static void update_wt(uint8_t wi, uint8_t d)
  */
 static struct msgb *usb_msg_alloc_hdr(uint8_t ep, uint8_t msg_class, uint8_t msg_type)
 {
+	/* Only allocate message if not too many are already in the queue */
+	struct llist_head *head = usb_get_queue(SIMTRACE_USB_EP_CARD_DATAIN);
+	if (!head) {
+		return NULL;
+	}
+	if (llist_count(head) > 5) {
+		return NULL;
+	}
 	struct msgb *usb_msg = usb_buf_alloc(SIMTRACE_USB_EP_CARD_DATAIN);
 	if (!usb_msg) {
 		return NULL;