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Subject: Re: [PATCH 1/5] net: qrtr: Move resume-tx transmission to recvmsg
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        "David S. Miller" <davem@davemloft.net>,
        Chris Lew <clew@codeaurora.org>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org
References: <20190508060643.30936-1-bjorn.andersson@linaro.org>
 <20190508060643.30936-2-bjorn.andersson@linaro.org>
From:   Arun Kumar Neelakantam <aneela@codeaurora.org>
Message-ID: <07d0f972-ce8b-1938-579f-733b1547e745@codeaurora.org>
Date:   Thu, 9 May 2019 15:53:49 +0530
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On 5/8/2019 11:36 AM, Bjorn Andersson wrote:
> The confirm-rx bit is used to implement a per port flow control, in
> order to make sure that no messages are dropped due to resource
> exhaustion. Move the resume-tx transmission to recvmsg to only confirm
> messages as they are consumed by the application.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>   net/qrtr/qrtr.c | 60 +++++++++++++++++++++++++++----------------------
>   1 file changed, 33 insertions(+), 27 deletions(-)
>
> diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> index dd0e97f4f6c0..07a35362fba2 100644
> --- a/net/qrtr/qrtr.c
> +++ b/net/qrtr/qrtr.c
> @@ -369,22 +369,11 @@ static void qrtr_port_put(struct qrtr_sock *ipc);
>   static void qrtr_node_rx_work(struct work_struct *work)
>   {
>   	struct qrtr_node *node = container_of(work, struct qrtr_node, work);
> -	struct qrtr_ctrl_pkt *pkt;
> -	struct sockaddr_qrtr dst;
> -	struct sockaddr_qrtr src;
>   	struct sk_buff *skb;
>   
>   	while ((skb = skb_dequeue(&node->rx_queue)) != NULL) {
>   		struct qrtr_sock *ipc;
> -		struct qrtr_cb *cb;
> -		int confirm;
> -
> -		cb = (struct qrtr_cb *)skb->cb;
> -		src.sq_node = cb->src_node;
> -		src.sq_port = cb->src_port;
> -		dst.sq_node = cb->dst_node;
> -		dst.sq_port = cb->dst_port;
> -		confirm = !!cb->confirm_rx;
> +		struct qrtr_cb *cb = (struct qrtr_cb *)skb->cb;
>   
>   		qrtr_node_assign(node, cb->src_node);
>   
> @@ -397,20 +386,6 @@ static void qrtr_node_rx_work(struct work_struct *work)
>   
>   			qrtr_port_put(ipc);
>   		}
> -
> -		if (confirm) {
> -			skb = qrtr_alloc_ctrl_packet(&pkt);
> -			if (!skb)
> -				break;
> -
> -			pkt->cmd = cpu_to_le32(QRTR_TYPE_RESUME_TX);
> -			pkt->client.node = cpu_to_le32(dst.sq_node);
> -			pkt->client.port = cpu_to_le32(dst.sq_port);
> -
> -			if (qrtr_node_enqueue(node, skb, QRTR_TYPE_RESUME_TX,
> -					      &dst, &src))
> -				break;
> -		}
>   	}
>   }
>   
> @@ -822,6 +797,34 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
>   	return rc;
>   }
>   
> +static int qrtr_resume_tx(struct qrtr_cb *cb)
This function name is adding some confusion with qrtr_tx_resume() in 
next patch. can you please rename this function to qrtr_send_resume_tx().
> +{
> +	struct sockaddr_qrtr remote = { AF_QIPCRTR, cb->src_node, cb->src_port };
> +	struct sockaddr_qrtr local = { AF_QIPCRTR, cb->dst_node, cb->dst_port };
> +	struct qrtr_ctrl_pkt *pkt;
> +	struct qrtr_node *node;
> +	struct sk_buff *skb;
> +	int ret;
> +
> +	node = qrtr_node_lookup(remote.sq_node);
> +	if (!node)
> +		return -EINVAL;
> +
> +	skb = qrtr_alloc_ctrl_packet(&pkt);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	pkt->cmd = cpu_to_le32(QRTR_TYPE_RESUME_TX);
> +	pkt->client.node = cpu_to_le32(cb->dst_node);
> +	pkt->client.port = cpu_to_le32(cb->dst_port);
> +
> +	ret = qrtr_node_enqueue(node, skb, QRTR_TYPE_RESUME_TX, &local, &remote);
> +
> +	qrtr_node_release(node);
> +
> +	return ret;
> +}
> +
>   static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
>   			size_t size, int flags)
>   {
> @@ -844,6 +847,7 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
>   		release_sock(sk);
>   		return rc;
>   	}
> +	cb = (struct qrtr_cb *)skb->cb;
>   
>   	copied = skb->len;
>   	if (copied > size) {
> @@ -857,7 +861,6 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
>   	rc = copied;
>   
>   	if (addr) {
> -		cb = (struct qrtr_cb *)skb->cb;
>   		addr->sq_family = AF_QIPCRTR;
>   		addr->sq_node = cb->src_node;
>   		addr->sq_port = cb->src_port;
> @@ -865,6 +868,9 @@ static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
>   	}
>   
>   out:
> +	if (cb->confirm_rx)
> +		qrtr_resume_tx(cb);
> +
>   	skb_free_datagram(sk, skb);
>   	release_sock(sk);
>