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Commit f1776dad authored by Rusty Russell's avatar Rusty Russell Committed by David S. Miller
Browse files

virtio_net: use non-reentrant workqueue. 



Michael S. Tsirkin also noticed that we could run the refill work
multiple CPUs: if we kick off a refill on one CPU and then on another,
they would both manipulate the queue at the same time (they use
napi_disable to avoid racing against the receive handler itself).

Tejun points out that this is what the WQ_NON_REENTRANT flag is for,
and that there is a convenient system kthread we can use.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b2baed69

drivers/net/virtio_net.c

+3 −3
Original line number Diff line number Diff line
@@ -508,7 +508,7 @@ static void refill_work(struct work_struct *work) 
	/* In theory, this can happen: if we don't get any buffers in

	 * we will *never* try to fill again. */

	if (still_empty)

		schedule_delayed_work(&vi->refill, HZ/2);

		queue_delayed_work(system_nrt_wq, &vi->refill, HZ/2);

}



static int virtnet_poll(struct napi_struct *napi, int budget)
@@ -527,7 +527,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget) 


	if (vi->num < vi->max / 2) {

		if (!try_fill_recv(vi, GFP_ATOMIC))

			schedule_delayed_work(&vi->refill, 0);

			queue_delayed_work(system_nrt_wq, &vi->refill, 0);

	}



	/* Out of packets? */
@@ -729,7 +729,7 @@ static int virtnet_open(struct net_device *dev) 


	/* Make sure we have some buffers: if oom use wq. */

	if (!try_fill_recv(vi, GFP_KERNEL))

		schedule_delayed_work(&vi->refill, 0);

		queue_delayed_work(system_nrt_wq, &vi->refill, 0);



	virtnet_napi_enable(vi);

	return 0;