netdev - Re: [PATCH net-next] net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)

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Date:	Fri, 17 Jun 2016 23:11:18 +0200
From:	Francois Romieu <romieu@...zoreil.com>
To:	Netanel Belgazal <netanel@...apurnalabs.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	linux-kernel@...r.kernel.org, zorik@...apurnalabs.com,
	saeed@...apurnalabs.com, alex@...apurnalabs.com, msw@...zon.com,
	aligouri@...zon.com, antoine.tenart@...e-electrons.com
Subject: Re: [PATCH net-next] net: ena: Add a driver for Amazon Elastic
 Network Adapters (ENA)

Netanel Belgazal <netanel@...apurnalabs.com> :
[...]

More stuff below.

> diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
> new file mode 100644
> index 0000000..357e10f
> --- /dev/null
> +++ b/drivers/net/ethernet/amazon/ena/ena_com.c
[...]
> +static int ena_get_dev_stats(struct ena_com_dev *ena_dev,
> +			     struct ena_admin_aq_get_stats_cmd *get_cmd,
> +			     struct ena_admin_acq_get_stats_resp *get_resp,

At first sight it should be possible avoid one pointer argument with:

struct ena_something {
	struct ena_admin_aq_get_stats_cmd cmd;
	struct ena_admin_acq_get_stats_resp resp;
	
};

[...]
> +int ena_com_get_dev_extended_stats(struct ena_com_dev *ena_dev, char *buff,
> +				   u32 len)

Where is it used ?

> +{
> +	int ret = 0;
> +	struct ena_admin_aq_get_stats_cmd get_cmd;
> +	struct ena_admin_acq_get_stats_resp get_resp;
> +	void *virt_addr;

	int rc = -ENOMEM;
	char *str;

> +	dma_addr_t phys_addr;
> +
> +	virt_addr = dma_alloc_coherent(ena_dev->dmadev,
> +				       len,
> +				       &phys_addr,
> +				       GFP_KERNEL | __GFP_ZERO);
> +	if (!virt_addr) {
> +		ret = -ENOMEM;
> +		goto done;
> +	}
> +	memset(&get_cmd, 0x0, sizeof(get_cmd));
> +	ret = ena_com_mem_addr_set(ena_dev,
> +				   &get_cmd.u.control_buffer.address,
> +				   phys_addr);
> +	if (unlikely(ret)) {
> +		ena_trc_err("memory address set failed\n");
> +		return ret;
> +	}
> +	get_cmd.u.control_buffer.length = len;
> +
> +	get_cmd.device_id = ena_dev->stats_func;
> +	get_cmd.queue_idx = ena_dev->stats_queue;
> +
> +	ret = ena_get_dev_stats(ena_dev, &get_cmd, &get_resp,
> +				ENA_ADMIN_GET_STATS_TYPE_EXTENDED);
> +	if (ret < 0)
> +		goto free_ext_stats_mem;
> +
> +	ret = snprintf(buff, len, "%s", (char *)virt_addr);

So ENA_ADMIN_GET_STATS_TYPE_EXTENDED fills a buffer with bytes in the
[0; 127] range, right ?

> +
> +free_ext_stats_mem:
> +	dma_free_coherent(ena_dev->dmadev, len, virt_addr, phys_addr);
> +done:
> +	return ret;
> +}
> +
> +int ena_com_set_dev_mtu(struct ena_com_dev *ena_dev, int mtu)
> +{
> +	struct ena_com_admin_queue *admin_queue;
> +	struct ena_admin_set_feat_cmd cmd;
> +	struct ena_admin_set_feat_resp resp;
> +	int ret = 0;

Should be -ENODEV or left uninitialized.

> +
> +	if (unlikely(!ena_dev)) {
> +		ena_trc_err("%s : ena_dev is NULL\n", __func__);
> +		return -ENODEV;
> +	}

Does it mean that ena_com_dev may go away while the net_device is in use ?

> +
> +	if (!ena_com_check_supported_feature_id(ena_dev, ENA_ADMIN_MTU)) {
> +		ena_trc_info("Feature %d isn't supported\n", ENA_ADMIN_MTU);
> +		return -EPERM;
> +	}

	rc = ena_com_check_supported_feature_id(...
	if (rc < 0) {
		ena_trc_info(...
		goto out;
	}
> +
> +	memset(&cmd, 0x0, sizeof(cmd));
> +	admin_queue = &ena_dev->admin_queue;
> +
> +	cmd.aq_common_descriptor.opcode = ENA_ADMIN_SET_FEATURE;
> +	cmd.aq_common_descriptor.flags = 0;
> +	cmd.feat_common.feature_id = ENA_ADMIN_MTU;
> +	cmd.u.mtu.mtu = mtu;
> +
> +	ret = ena_com_execute_admin_command(admin_queue,
> +					    (struct ena_admin_aq_entry *)&cmd,
> +					    sizeof(cmd),
> +					    (struct ena_admin_acq_entry *)&resp,
> +					    sizeof(resp));
> +
> +	if (unlikely(ret)) {
> +		ena_trc_err("Failed to set mtu %d. error: %d\n", mtu, ret);
> +		return -EINVAL;

ena_com_execute_admin_command should return a proper status code.

[...]
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
new file mode 100644
index 0000000..e49ba43
--- /dev/null
[...]
+static inline void ena_com_update_intr_reg(struct ena_eth_io_intr_reg *intr_reg,
+					   u32 rx_delay_interval,
+					   u32 tx_delay_interval,
+					   bool unmask)
+{
+	intr_reg->intr_control = 0;
+	intr_reg->intr_control |= rx_delay_interval &
+		ENA_ETH_IO_INTR_REG_RX_INTR_DELAY_MASK;
+
+	intr_reg->intr_control |=
+		(tx_delay_interval << ENA_ETH_IO_INTR_REG_TX_INTR_DELAY_SHIFT)
+		& ENA_ETH_IO_INTR_REG_RX_INTR_DELAY_MASK;
                                      ^^ TX ?

Extra: you should not return NETDEV_TX_BUSY in the xmit handler while
queueing is still enabled. Please drop packet and return NETDEV_TX_OK.

-- 
Ueimor