On Wed, Jun 05, 2013 at 02:36:25PM +0800, Jason Wang wrote:
> There's no need to add self to waitqueue if doing a nonblock read. This could
> help to avoid the spinlock contention.
>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> drivers/net/macvtap.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 5e485e3..8949631 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -845,7 +845,9 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q,
> struct kiocb *iocb,
> ssize_t ret = 0;
>
> while (len) {
> - prepare_to_wait(sk_sleep(&q->sk), &wait, TASK_INTERRUPTIBLE);
> + if (!noblock)
> + prepare_to_wait(sk_sleep(&q->sk), &wait,
> + TASK_INTERRUPTIBLE);
>
> /* Read frames from the queue */
> skb = skb_dequeue(&q->sk.sk_receive_queue);
> @@ -867,7 +869,8 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q,
> struct kiocb *iocb,
> break;
> }
>
> - finish_wait(sk_sleep(&q->sk), &wait);
> + if (!noblock)
> + finish_wait(sk_sleep(&q->sk), &wait);
> return ret;
> }
>
> --
> 1.7.1
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