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, 14 insertions, 10 deletions

diff --git a/drivers/staging/batman-adv/device.c b/drivers/staging/batman-adv/device.c
index 92cf8d56a5f..ab2b0b17d9e 100644
--- a/drivers/staging/batman-adv/device.c
+++ b/drivers/staging/batman-adv/device.c
@@ -133,8 +133,9 @@ int bat_device_release(struct inode *inode, struct file *file)
 		(struct device_client *)file->private_data;
 	struct device_packet *device_packet;
 	struct list_head *list_pos, *list_pos_tmp;
+	unsigned long flags;
 
-	spin_lock(&device_client->lock);
+	spin_lock_irqsave(&device_client->lock, flags);
 
 	/* for all packets in the queue ... */
 	list_for_each_safe(list_pos, list_pos_tmp, &device_client->queue_list) {
@@ -146,7 +147,7 @@ int bat_device_release(struct inode *inode, struct file *file)
 	}
 
 	device_client_hash[device_client->index] = NULL;
-	spin_unlock(&device_client->lock);
+	spin_unlock_irqrestore(&device_client->lock, flags);
 
 	kfree(device_client);
 	dec_module_count();
@@ -161,6 +162,7 @@ ssize_t bat_device_read(struct file *file, char __user *buf, size_t count,
 		(struct device_client *)file->private_data;
 	struct device_packet *device_packet;
 	int error;
+	unsigned long flags;
 
 	if ((file->f_flags & O_NONBLOCK) && (device_client->queue_len == 0))
 		return -EAGAIN;
@@ -177,14 +179,14 @@ ssize_t bat_device_read(struct file *file, char __user *buf, size_t count,
 	if (error)
 		return error;
 
-	spin_lock(&device_client->lock);
+	spin_lock_irqsave(&device_client->lock, flags);
 
 	device_packet = list_first_entry(&device_client->queue_list,
 					 struct device_packet, list);
 	list_del(&device_packet->list);
 	device_client->queue_len--;
 
-	spin_unlock(&device_client->lock);
+	spin_unlock_irqrestore(&device_client->lock, flags);
 
 	error = __copy_to_user(buf, &device_packet->icmp_packet,
 			       sizeof(struct icmp_packet));
@@ -205,6 +207,7 @@ ssize_t bat_device_write(struct file *file, const char __user *buff,
 	struct icmp_packet icmp_packet;
 	struct orig_node *orig_node;
 	struct batman_if *batman_if;
+	unsigned long flags;
 
 	if (len < sizeof(struct icmp_packet)) {
 		bat_dbg(DBG_BATMAN, "batman-adv:Error - can't send packet from char device: invalid packet size\n");
@@ -239,7 +242,7 @@ ssize_t bat_device_write(struct file *file, const char __user *buff,
 	if (atomic_read(&module_state) != MODULE_ACTIVE)
 		goto dst_unreach;
 
-	spin_lock(&orig_hash_lock);
+	spin_lock_irqsave(&orig_hash_lock, flags);
 	orig_node = ((struct orig_node *)hash_find(orig_hash, icmp_packet.dst));
 
 	if (!orig_node)
@@ -261,11 +264,11 @@ ssize_t bat_device_write(struct file *file, const char __user *buff,
 			sizeof(struct icmp_packet),
 			batman_if, orig_node->router->addr);
 
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 	goto out;
 
 unlock:
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 dst_unreach:
 	icmp_packet.msg_type = DESTINATION_UNREACHABLE;
 	bat_device_add_packet(device_client, &icmp_packet);
@@ -290,6 +293,7 @@ void bat_device_add_packet(struct device_client *device_client,
 			   struct icmp_packet *icmp_packet)
 {
 	struct device_packet *device_packet;
+	unsigned long flags;
 
 	device_packet = kmalloc(sizeof(struct device_packet), GFP_KERNEL);
 
@@ -300,12 +304,12 @@ void bat_device_add_packet(struct device_client *device_client,
 	memcpy(&device_packet->icmp_packet, icmp_packet,
 	       sizeof(struct icmp_packet));
 
-	spin_lock(&device_client->lock);
+	spin_lock_irqsave(&device_client->lock, flags);
 
 	/* while waiting for the lock the device_client could have been
 	 * deleted */
 	if (!device_client_hash[icmp_packet->uid]) {
-		spin_unlock(&device_client->lock);
+		spin_unlock_irqrestore(&device_client->lock, flags);
 		kfree(device_packet);
 		return;
 	}
@@ -322,7 +326,7 @@ void bat_device_add_packet(struct device_client *device_client,
 		device_client->queue_len--;
 	}
 
-	spin_unlock(&device_client->lock);
+	spin_unlock_irqrestore(&device_client->lock, flags);
 
 	wake_up(&device_client->queue_wait);
 }