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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Maxime Coquelin
> Sent: Friday, March 22, 2019 11:00 AM
> To: Hajkowski, MarcinX <marcinx.hajkowski@intel.com>; Hunt, David <david.hunt@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 2/4] power: extend guest channel api for reading
> 
> 
> 
> 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,

+1 here and in other places.
please follow dpdk coding style convention.

> 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;
> > +}
> > +