* [PATCH] virtio_net: use non-reentrant workqueue.
[not found] <87ehvogitg.fsf@rustcorp.com.au>
@ 2011-12-29 10:43 ` Rusty Russell
2011-12-29 20:33 ` Michael S. Tsirkin
1 sibling, 0 replies; 3+ messages in thread
From: Rusty Russell @ 2011-12-29 10:43 UTC (permalink / raw)
To: netdev; +Cc: Michael S. Tsirkin, Tejun Heo
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: Rusty Russell <rusty@rustcorp.com.au>
---
drivers/net/virtio_net.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -507,7 +507,7 @@ static void refill_work(struct work_stru
/* 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)
@@ -526,7 +526,7 @@ again:
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? */
@@ -727,7 +727,7 @@ static int virtnet_open(struct net_devic
/* 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;
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] virtio_net: use non-reentrant workqueue.
[not found] <87ehvogitg.fsf@rustcorp.com.au>
2011-12-29 10:43 ` [PATCH] virtio_net: use non-reentrant workqueue Rusty Russell
@ 2011-12-29 20:33 ` Michael S. Tsirkin
2011-12-29 21:44 ` David Miller
1 sibling, 1 reply; 3+ messages in thread
From: Michael S. Tsirkin @ 2011-12-29 20:33 UTC (permalink / raw)
To: Rusty Russell; +Cc: netdev, Tejun Heo
On Thu, Dec 29, 2011 at 01:55:47PM +1030, Rusty Russell wrote:
> 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: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> drivers/net/virtio_net.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -507,7 +507,7 @@ static void refill_work(struct work_stru
> /* 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)
> @@ -526,7 +526,7 @@ again:
>
> 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? */
> @@ -727,7 +727,7 @@ static int virtnet_open(struct net_devic
>
> /* 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;
^ permalink raw reply [flat|nested] 3+ messages in thread