P2P: Limit number of SD retries during find

Commit 7139cf4a4f ('P2P: Decrement
sd_pending_bcast_queries when sd returns success') added support for
retrying P2P SD queries. However, it did this without limiting how many
retries are allowed. This can result in excessive number of retries if a
peer device does not show up on its Listen channel and there is a
pending SD query to it. Limit the maximum number of SD retries to 100
per p2p_find operation for each peer to avoid unlimited retries.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

src/p2p/p2p.c

@@ -348,8 +348,10 @@ int p2p_listen(struct p2p_data *p2p, unsigned int timeout)
 static void p2p_device_clear_reported(struct p2p_data *p2p)
 {
 	struct p2p_device *dev;
-	dl_list_for_each(dev, &p2p->devices, struct p2p_device, list)
+	dl_list_for_each(dev, &p2p->devices, struct p2p_device, list) {
 		dev->flags &= ~P2P_DEV_REPORTED;
+		dev->sd_reqs = 0;
+	}
 }
 
 

src/p2p/p2p_i.h

@@ -105,6 +105,7 @@ struct p2p_device {
 	unsigned int wait_count;
 	unsigned int connect_reqs;
 	unsigned int invitation_reqs;
+	unsigned int sd_reqs;
 
 	u16 ext_listen_period;
 	u16 ext_listen_interval;

src/p2p/p2p_sd.c

@@ -75,16 +75,25 @@ struct p2p_sd_query * p2p_pending_sd_req(struct p2p_data *p2p,
 				return NULL;
 			/* query number that needs to be send to the device */
 			if (count == dev->sd_pending_bcast_queries - 1)
-				return q;
+				goto found;
 			count++;
 		}
 		if (!q->for_all_peers &&
 		    os_memcmp(q->peer, dev->info.p2p_device_addr, ETH_ALEN) ==
 		    0)
-			return q;
+			goto found;
 	}
 
 	return NULL;
+
+found:
+	if (dev->sd_reqs > 100) {
+		p2p_dbg(p2p, "Too many SD request attempts to " MACSTR
+			" - skip remaining queries",
+			MAC2STR(dev->info.p2p_device_addr));
+		return NULL;
+	}
+	return q;
 }
 
 
@@ -287,6 +296,7 @@ int p2p_start_sd(struct p2p_data *p2p, struct p2p_device *dev)
 	if (req == NULL)
 		return -1;
 
+	dev->sd_reqs++;
 	p2p->sd_peer = dev;
 	p2p->sd_query = query;
 	p2p->pending_action_state = P2P_PENDING_SD;