Re: [dpdk-dev] [PATCH v3 2/4] power: extend guest channel api for reading

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 3/21/19 11:55 AM, Hajkowski wrote:
> From: Marcin Hajkowski <marcinx.hajkowski@intel.com>
> 
> Added new experimental API rte_power_guest_channel_receive_msg
> which gives possibility to receive messages send to guest.
> 
> Signed-off-by: Marcin Hajkowski <marcinx.hajkowski@intel.com>
> ---
>   lib/librte_power/channel_commands.h    |  5 ++
>   lib/librte_power/guest_channel.c       | 65 ++++++++++++++++++++++++++
>   lib/librte_power/guest_channel.h       | 35 ++++++++++++++
>   lib/librte_power/rte_power_version.map |  1 +
>   4 files changed, 106 insertions(+)
> 
> diff --git a/lib/librte_power/channel_commands.h b/lib/librte_power/channel_commands.h
> index e7b93a797..33fd53a6d 100644
> --- a/lib/librte_power/channel_commands.h
> +++ b/lib/librte_power/channel_commands.h
> @@ -28,6 +28,11 @@ extern "C" {
>   #define CPU_POWER_SCALE_MIN     4
>   #define CPU_POWER_ENABLE_TURBO  5
>   #define CPU_POWER_DISABLE_TURBO 6
> +
> +/* Generic Power Command Response */
> +#define CPU_POWER_CMD_ACK       1
> +#define CPU_POWER_CMD_NACK      2
> +
>   #define HOURS 24
>   
>   #define MAX_VFS 10
> diff --git a/lib/librte_power/guest_channel.c b/lib/librte_power/guest_channel.c
> index 9cf7d2cb2..3213fa769 100644
> --- a/lib/librte_power/guest_channel.c
> +++ b/lib/librte_power/guest_channel.c
> @@ -10,6 +10,7 @@
>   #include <fcntl.h>
>   #include <string.h>
>   #include <errno.h>
> +#include <poll.h>
>   
>   
>   #include <rte_log.h>
> @@ -19,6 +20,9 @@
>   
>   #define RTE_LOGTYPE_GUEST_CHANNEL RTE_LOGTYPE_USER1
>   
> +/* Timeout for incoming message in milliseconds. */
> +#define TIMEOUT 10
> +
>   static int global_fds[RTE_MAX_LCORE] = { [0 ... RTE_MAX_LCORE-1] = -1 };
>   
>   int
> @@ -125,6 +129,67 @@ int rte_power_guest_channel_send_msg(struct channel_packet *pkt,
>   	return guest_channel_send_msg(pkt, lcore_id);
>   }
>   
> +int power_guest_channel_read_msg(struct channel_packet *pkt,
> +			unsigned int lcore_id)
> +{
> +	int ret;
> +
> +	struct pollfd fds;
> +	fds.fd = global_fds[lcore_id];
> +	fds.events = POLLIN;
> +
> +	ret = poll(&fds, 1, TIMEOUT);
> +	if (ret == 0) {
> +		RTE_LOG(DEBUG, GUEST_CHANNEL, "Timeout occurs during poll function.\n");
> +		return -1;
> +	} else if (ret < 0) {
> +		RTE_LOG(ERR, GUEST_CHANNEL, "Error occurred during poll function: %s\n",
> +				strerror(ret));
> +		return -1;
> +	}
> +
> +	void *buffer = pkt;

I would prefer it to be declared at the beginning of the function,
but at least, declare it just before the while loop.

> +
> +	if (lcore_id >= RTE_MAX_LCORE) {
> +		RTE_LOG(ERR, GUEST_CHANNEL, "Channel(%u) is out of range 0...%d\n",
> +				lcore_id, RTE_MAX_LCORE-1);
> +		return -1;
> +	}
> +
> +	if (global_fds[lcore_id] < 0) {
> +		RTE_LOG(ERR, GUEST_CHANNEL, "Channel is not connected\n");
> +		return -1;
> +	}
> +
> +	int buffer_len = sizeof(*pkt);
> +
> +	while (buffer_len > 0) {
> +		ret = read(global_fds[lcore_id],
> +				buffer, buffer_len);
> +		if (ret < 0) {
> +			if (errno == EINTR)
> +				continue;
> +			return -1;
> +		}
> +		/* No data has been read, this can indicate not
> +		 * consistent buffer_len with actual data size.
> +		 */
> +		if (ret == 0) {
> +			RTE_LOG(ERR, GUEST_CHANNEL, "No more data has been read.\n");
> +			return -1;
> +		}
> +		buffer = (char *)buffer + ret;
> +		buffer_len -= ret;
> +	}
> +
> +	return 0;
> +}
> +