[PATCH] vhost: use try_lock in rte_vhost_vring_call

[Xia, Chenbo]

Hi Changpeng,

> -----Original Message-----
> From: Liu, Changpeng <changpeng.liu at intel.com>
> Sent: Tuesday, September 6, 2022 10:22 AM
> To: dev at dpdk.org
> Cc: Liu, Changpeng <changpeng.liu at intel.com>; Maxime Coquelin
> <maxime.coquelin at redhat.com>; Xia, Chenbo <chenbo.xia at intel.com>
> Subject: [PATCH] vhost: use try_lock in rte_vhost_vring_call
> 
> Note that this function is in data path, so the thread context
> may not same as socket messages processing context, by using
> try_lock here, users can have another try in case of VQ's access
> lock is held by `vhost-events` thread.

Better to describe the issue this patch wants to fix and how does
it fix.

I remember it's a bz issue, do you want to backport? And it has
some bz ID, we need to add it in commit message.

> 
> Signed-off-by: Changpeng Liu <changpeng.liu at intel.com>
> ---
>  lib/vhost/vhost.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index 60cb05a0ff..072d2acb7b 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)
>  	if (!vq)
>  		return -1;
> 
> -	rte_spinlock_lock(&vq->access_lock);
> +	if (!rte_spinlock_trylock(&vq->access_lock)) {
> +		VHOST_LOG_CONFIG(dev->ifname, DEBUG,

Should use VHOST_LOG_DATA

Thanks,
Chenbo

> +			"failed to kick guest, virtqueue busy.\n");
> +		return -1;
> +	}
> 
>  	if (vq_is_packed(dev))
>  		vhost_vring_call_packed(dev, vq);
> --
> 2.21.3