tun: fix multiqueue rx

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

---
  drivers/net/tun.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

drivers/net/tun.c +1 -0

index a65779c6d72f..4e306ff3501c 100644
@@ -1536,6 +1536,7 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
 
  	if (!rx_batched || (!more && skb_queue_empty(queue))) {
  		local_bh_disable();
+		skb_record_rx_queue(skb, tfile->queue_index);
  		netif_receive_skb(skb);
  		local_bh_enable();
  		return;

@@ -1555,8 +1556,11 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
  		struct sk_buff *nskb;
 

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

---
  drivers/net/tun.c | 7 ++++++-
  1 file changed, 6 insertions(+), 1 deletion(-)

drivers/net/tun.c +5 -1

index a65779c6d72f..ce8620f3ea5e 100644
@@ -1536,6 +1536,7 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
 
  	if (!rx_batched || (!more && skb_queue_empty(queue))) {
  		local_bh_disable();
+		skb_record_rx_queue(skb, tfile->queue_index);
  		netif_receive_skb(skb);
  		local_bh_enable();
  		return;

@@ -1555,8 +1556,11 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
  		struct sk_buff *nskb;
 
  		local_bh_disable();
-		while ((nskb = __skb_dequeue(&process_queue)))
+		while ((nskb = __skb_dequeue(&process_queue))) {
+			skb_record_rx_queue(nskb, tfile->queue_index);
  			netif_receive_skb(nskb);
+		}
+		skb_record_rx_queue(skb, tfile->queue_index);
  		netif_receive_skb(skb);
  		local_bh_enable();
  	}

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

---
 drivers/net/tun.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

drivers/net/tun.c +6 -1

index a65779c6d72f..ce8620f3ea5e 100644
@@ -1536,6 +1536,7 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
 
 	if (!rx_batched || (!more && skb_queue_empty(queue))) {
 		local_bh_disable();
+		skb_record_rx_queue(skb, tfile->queue_index);
 		netif_receive_skb(skb);
 		local_bh_enable();
 		return;

@@ -1555,8 +1556,11 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
 		struct sk_buff *nskb;
 
 		local_bh_disable();
-		while ((nskb = __skb_dequeue(&process_queue)))
+		while ((nskb = __skb_dequeue(&process_queue))) {
+			skb_record_rx_queue(nskb, tfile->queue_index);
 			netif_receive_skb(nskb);
+		}
+		skb_record_rx_queue(skb, tfile->queue_index);
 		netif_receive_skb(skb);
 		local_bh_enable();
 	}

@@ -2452,6 +2456,7 @@ static int tun_xdp_one(struct tun_struct *tun,
 	    !tfile->detached)
 		rxhash = __skb_get_hash_symmetric(skb);
 
+	skb_record_rx_queue(skb, tfile->queue_index);
 	netif_receive_skb(skb);
 
 	stats = get_cpu_ptr(tun->pcpu_stats);

Signature · 1 line

2.15.2 (Apple Git-101.1)

Quoted 22 lines · Matthew Cover

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Quoted 4 lines

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

Acked-by Michael S. Tsirkin <[email protected]>

stable material?

Quoted 39 lines

---
 drivers/net/tun.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

drivers/net/tun.c +6 -2

index a65779c6d72f..ce8620f3ea5e 100644
@@ -1536,6 +1536,7 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
 
      if (!rx_batched || (!more && skb_queue_empty(queue))) {
              local_bh_disable();
+             skb_record_rx_queue(skb, tfile->queue_index);
              netif_receive_skb(skb);
              local_bh_enable();
              return;

@@ -1555,8 +1556,11 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
              struct sk_buff *nskb;
 
              local_bh_disable();
-             while ((nskb = __skb_dequeue(&process_queue)))
+             while ((nskb = __skb_dequeue(&process_queue))) {
+                     skb_record_rx_queue(nskb, tfile->queue_index);
                      netif_receive_skb(nskb);
+             }
+             skb_record_rx_queue(skb, tfile->queue_index);
              netif_receive_skb(skb);
              local_bh_enable();
      }

@@ -2452,6 +2456,7 @@ static int tun_xdp_one(struct tun_struct *tun,
          !tfile->detached)
              rxhash = __skb_get_hash_symmetric(skb);
 
+     skb_record_rx_queue(skb, tfile->queue_index);
      netif_receive_skb(skb);
 
      stats = get_cpu_ptr(tun->pcpu_stats);
--

2.15.2 (Apple Git-101.1)

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>

When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.

Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.

The rx traffic can be generated by either of the following.
1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors
2. tx from a qemu vm with a tap multiqueue netdev

The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case).
1. a simple netmap program which opens and reads from per-queue descriptors
2. configuring RPS and doing per-cpu captures with rxtxcpu

Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.

Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.

Signed-off-by Matthew Cover <[email protected]>