Staging: batman-adv: receive packets directly using skbs

This patch removes the (ugly and racy) packet receiving thread and the
kernel socket usage. Instead, packets are received directly by registering
the ethernet type and handling skbs instead of self-allocated buffers.

Some consequences and comments:

 * we don't copy the payload data when forwarding/sending/receiving data
   anymore. This should boost performance.
 * packets from/to different interfaces can be (theoretically) processed
   simultaneously. Only the big originator hash lock might be in the way.
 * no more polling or sleeping/wakeup/scheduling issues when receiving
   packets
 * this might introduce new race conditions.
 * aggregation and vis code still use packet buffers and are not (yet)
   converted.
 * all spinlocks were converted to irqsave/restore versions to solve
   some lifelock issues when preempted. This might be overkill, some
   of these locks might be reverted later.
 * skb copies are only done if neccesary to avoid overhead

performance differences:

 * we made some "benchmarks" with intel laptops.
 * bandwidth on Gigabit Ethernet increased from ~500 MBit/s to ~920 MBit/s
 * ping latency decresed from ~2ms to ~0.2 ms

I did some tests on my 9 node qemu environment and could confirm that
usual sending/receiving, forwarding, vis, batctl ping etc works.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Acked-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Acked-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 32 insertions, 23 deletions

diff --git a/drivers/staging/batman-adv/vis.c b/drivers/staging/batman-adv/vis.c
index 62ee773..1912979 100644
--- a/drivers/staging/batman-adv/vis.c
+++ b/drivers/staging/batman-adv/vis.c
@@ -52,12 +52,13 @@ static void free_info(void *data)
 /* set the mode of the visualization to client or server */
 void vis_set_mode(int mode)
 {
-	spin_lock(&vis_hash_lock);
+	unsigned long flags;
+	spin_lock_irqsave(&vis_hash_lock, flags);
 
 	if (my_vis_info != NULL)
 		my_vis_info->packet.vis_type = mode;
 
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 }
 
 /* is_vis_server(), locked outside */
@@ -74,10 +75,11 @@ static int is_vis_server_locked(void)
 int is_vis_server(void)
 {
 	int ret = 0;
+	unsigned long flags;
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	ret = is_vis_server_locked();
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 
 	return ret;
 }
@@ -269,8 +271,9 @@ void receive_server_sync_packet(struct vis_packet *vis_packet, int vis_info_len)
 {
 	struct vis_info *info;
 	int is_new;
+	unsigned long flags;
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	info = add_packet(vis_packet, vis_info_len, &is_new);
 	if (info == NULL)
 		goto end;
@@ -283,7 +286,7 @@ void receive_server_sync_packet(struct vis_packet *vis_packet, int vis_info_len)
 			list_add_tail(&info->send_list, &send_list);
 	}
 end:
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 }
 
 /* handle an incoming client update packet and schedule forward if needed. */
@@ -292,12 +295,13 @@ void receive_client_update_packet(struct vis_packet *vis_packet,
 {
 	struct vis_info *info;
 	int is_new;
+	unsigned long flags;
 
 	/* clients shall not broadcast. */
 	if (is_bcast(vis_packet->target_orig))
 		return;
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	info = add_packet(vis_packet, vis_info_len, &is_new);
 	if (info == NULL)
 		goto end;
@@ -319,7 +323,7 @@ void receive_client_update_packet(struct vis_packet *vis_packet,
 			list_add_tail(&info->send_list, &send_list);
 	}
 end:
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 }
 
 /* Walk the originators and find the VIS server with the best tq. Set the packet
@@ -370,7 +374,7 @@ static int generate_vis_packet(void)
 
 	info->first_seen = jiffies;
 
-	spin_lock(&orig_hash_lock);
+	spin_lock_irqsave(&orig_hash_lock, flags);
 	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
 	info->packet.ttl = TTL;
 	info->packet.seqno++;
@@ -379,7 +383,7 @@ static int generate_vis_packet(void)
 	if (!is_vis_server_locked()) {
 		best_tq = find_best_vis_server(info);
 		if (best_tq < 0) {
-			spin_unlock(&orig_hash_lock);
+			spin_unlock_irqrestore(&orig_hash_lock, flags);
 			return -1;
 		}
 	}
@@ -403,13 +407,13 @@ static int generate_vis_packet(void)
 			info->packet.entries++;
 
 			if (vis_packet_full(info)) {
-				spin_unlock(&orig_hash_lock);
+				spin_unlock_irqrestore(&orig_hash_lock, flags);
 				return 0;
 			}
 		}
 	}
 
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 
 	spin_lock_irqsave(&hna_local_hash_lock, flags);
 	while (hash_iterate(hna_local_hash, &hashit_local)) {
@@ -450,8 +454,9 @@ static void broadcast_vis_packet(struct vis_info *info, int packet_length)
 {
 	HASHIT(hashit);
 	struct orig_node *orig_node;
+	unsigned long flags;
 
-	spin_lock(&orig_hash_lock);
+	spin_lock_irqsave(&orig_hash_lock, flags);
 
 	/* send to all routers in range. */
 	while (hash_iterate(orig_hash, &hashit)) {
@@ -478,14 +483,15 @@ static void broadcast_vis_packet(struct vis_info *info, int packet_length)
 		}
 	}
 	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 }
 
 static void unicast_vis_packet(struct vis_info *info, int packet_length)
 {
 	struct orig_node *orig_node;
+	unsigned long flags;
 
-	spin_lock(&orig_hash_lock);
+	spin_lock_irqsave(&orig_hash_lock, flags);
 	orig_node = ((struct orig_node *)
 		     hash_find(orig_hash, info->packet.target_orig));
 
@@ -496,7 +502,7 @@ static void unicast_vis_packet(struct vis_info *info, int packet_length)
 				orig_node->batman_if,
 				orig_node->router->addr);
 	}
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 }
 
 /* only send one vis packet. called from send_vis_packets() */
@@ -526,8 +532,9 @@ static void send_vis_packet(struct vis_info *info)
 static void send_vis_packets(struct work_struct *work)
 {
 	struct vis_info *info, *temp;
+	unsigned long flags;
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	purge_vis_packets();
 
 	if (generate_vis_packet() == 0)
@@ -538,7 +545,7 @@ static void send_vis_packets(struct work_struct *work)
 		list_del_init(&info->send_list);
 		send_vis_packet(info);
 	}
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 	start_vis_timer();
 }
 static DECLARE_DELAYED_WORK(vis_timer_wq, send_vis_packets);
@@ -547,10 +554,11 @@ static DECLARE_DELAYED_WORK(vis_timer_wq, send_vis_packets);
  * initialized (e.g. bat0 is initialized, interfaces have been added) */
 int vis_init(void)
 {
+	unsigned long flags;
 	if (vis_hash)
 		return 1;
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 
 	vis_hash = hash_new(256, vis_info_cmp, vis_info_choose);
 	if (!vis_hash) {
@@ -588,12 +596,12 @@ int vis_init(void)
 		goto err;
 	}
 
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 	start_vis_timer();
 	return 1;
 
 err:
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 	vis_quit();
 	return 0;
 }
@@ -601,17 +609,18 @@ err:
 /* shutdown vis-server */
 void vis_quit(void)
 {
+	unsigned long flags;
 	if (!vis_hash)
 		return;
 
 	cancel_delayed_work_sync(&vis_timer_wq);
 
-	spin_lock(&vis_hash_lock);
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	/* properly remove, kill timers ... */
 	hash_delete(vis_hash, free_info);
 	vis_hash = NULL;
 	my_vis_info = NULL;
-	spin_unlock(&vis_hash_lock);
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 }
 
 /* schedule packets for (re)transmission */