net: dsa: sja1105: bring deferred xmit implementation in line with ocelot-8021q
When the ocelot-8021q driver was converted to deferred xmit as part of commit 8d5f7954 ("net: dsa: felix: break at first CPU port during init and teardown"), the deferred implementation was deliberately made subtly different from what sja1105 has. The implementation differences lied on the following observations: - There might be a race between these two lines in tag_sja1105.c: skb_queue_tail(&sp->xmit_queue, skb_get(skb)); kthread_queue_work(sp->xmit_worker, &sp->xmit_work); and the skb dequeue logic in sja1105_port_deferred_xmit(). For example, the xmit_work might be already queued, however the work item has just finished walking through the skb queue. Because we don't check the return code from kthread_queue_work, we don't do anything if the work item is already queued. However, nobody will take that skb and send it, at least until the next timestampable skb is sent. This creates additional (and avoidable) TX timestamping latency. To close that race, what the ocelot-8021q driver does is it doesn't keep a single work item per port, and a skb timestamping queue, but rather dynamically allocates a work item per packet. - It is also unnecessary to have more than one kthread that does the work. So delete the per-port kthread allocations and replace them with a single kthread which is global to the switch. This change brings the two implementations in line by applying those observations to the sja1105 driver as well. Signed-off-by:Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
a3d74295
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