Commit 8e2f1a63 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

packet: fix packet_direct_xmit for BQL enabled drivers 



Currently, in packet_direct_xmit() we test the assigned netdevice queue
for netif_xmit_frozen_or_stopped() before doing an ndo_start_xmit().

This can have the side-effect that BQL enabled drivers which make use
of netdev_tx_sent_queue() internally, set __QUEUE_STATE_STACK_XOFF from
within the stack and would not fully fill the device's TX ring from
packet sockets with PACKET_QDISC_BYPASS enabled.

Instead, use a test without BQL bit so that bursts can be absorbed
into the NICs TX ring. Fix and code suggested by Eric Dumazet, thanks!

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0f97ede4

include/linux/netdevice.h

+19 −5
Original line number Diff line number Diff line
@@ -519,11 +519,18 @@ enum netdev_queue_state_t { 
	__QUEUE_STATE_DRV_XOFF,

	__QUEUE_STATE_STACK_XOFF,

	__QUEUE_STATE_FROZEN,

#define QUEUE_STATE_ANY_XOFF ((1 << __QUEUE_STATE_DRV_XOFF)		| \

			      (1 << __QUEUE_STATE_STACK_XOFF))

#define QUEUE_STATE_ANY_XOFF_OR_FROZEN (QUEUE_STATE_ANY_XOFF		| \

					(1 << __QUEUE_STATE_FROZEN))

};



#define QUEUE_STATE_DRV_XOFF	(1 << __QUEUE_STATE_DRV_XOFF)

#define QUEUE_STATE_STACK_XOFF	(1 << __QUEUE_STATE_STACK_XOFF)

#define QUEUE_STATE_FROZEN	(1 << __QUEUE_STATE_FROZEN)



#define QUEUE_STATE_ANY_XOFF	(QUEUE_STATE_DRV_XOFF | QUEUE_STATE_STACK_XOFF)

#define QUEUE_STATE_ANY_XOFF_OR_FROZEN (QUEUE_STATE_ANY_XOFF | \

					QUEUE_STATE_FROZEN)

#define QUEUE_STATE_DRV_XOFF_OR_FROZEN (QUEUE_STATE_DRV_XOFF | \

					QUEUE_STATE_FROZEN)



/*

 * __QUEUE_STATE_DRV_XOFF is used by drivers to stop the transmit queue.  The

 * netif_tx_* functions below are used to manipulate this flag.  The
@@ -2252,11 +2259,18 @@ static inline bool netif_xmit_stopped(const struct netdev_queue *dev_queue) 
	return dev_queue->state & QUEUE_STATE_ANY_XOFF;

}



static inline bool netif_xmit_frozen_or_stopped(const struct netdev_queue *dev_queue)

static inline bool

netif_xmit_frozen_or_stopped(const struct netdev_queue *dev_queue)

{

	return dev_queue->state & QUEUE_STATE_ANY_XOFF_OR_FROZEN;

}



static inline bool

netif_xmit_frozen_or_drv_stopped(const struct netdev_queue *dev_queue)

{

	return dev_queue->state & QUEUE_STATE_DRV_XOFF_OR_FROZEN;

}



static inline void netdev_tx_sent_queue(struct netdev_queue *dev_queue,

					unsigned int bytes)

{

net/packet/af_packet.c

+1 −1
Original line number Diff line number Diff line
@@ -261,7 +261,7 @@ static int packet_direct_xmit(struct sk_buff *skb) 
	local_bh_disable();



	HARD_TX_LOCK(dev, txq, smp_processor_id());

	if (!netif_xmit_frozen_or_stopped(txq)) {

	if (!netif_xmit_frozen_or_drv_stopped(txq)) {

		ret = ops->ndo_start_xmit(skb, dev);

		if (ret == NETDEV_TX_OK)

			txq_trans_update(txq);

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