MC_GETSTAT(9E) Driver Entry Points MC_GETSTAT(9E)

mc_getstat
get device statistics information

#include <sys/mac_provider.h>
#include <sys/mac_ether.h>

int
prefix_m_getstat(void *driver, uint_t stat, uint64_t *stat_value);

illumos DDI specific

driver
A pointer to the driver's private data that was passed in via the m_pdata member of the mac_register(9S) structure to the mac_register(9F) function.
stat
The numeric identifier of a statistic.
stat_value
A pointer to a 64-bit unsigned value in which the device driver should place the statistic.

The mc_getstat() entry point is used to get statistics from the device driver. Statistics are stored as monotonic values. They should only ever increase over the lifetime of a device, resetting only as part of the instance of a device attaching and detaching. When hardware has values that may overflow, it is up to the device driver to store them as a 64-bit quantity that does not overflow in its soft state.

Most device drivers will use a switch statement, switching on the value of the statistic stat. The full list of supported statistics is available in the STATISTICS section of mac(9E).

If a device driver recognizes the value of stat, then it should store the current 64-bit unsigned integer into stat_value. If the device driver does not support the statistic or does not recognize the requested statistic, then it should not set anything in stat_value and instead return ENOTSUP.

The device driver can obtain access to its soft state through the driver member. It should be cast to the appropriate structure. The device driver should employ any necessary locking to access the statistic members of its soft state to ensure that the data is properly serialized.

Upon successful completion, the device driver should fill in stat_value and return 0. Otherwise it should return a non-zero error number to indicate an error occurred.

The following example shows how a driver might structure its mc_getstat() entry point.
#include <sys/mac_provider.h>
#include <sys/mac_ether.h>

/*
 * Note, this example merely shows the structure of the function. For
 * the purpose of this example, we assume that we have a device which
 * has members that indicate its stats and that it has a lock which is
 * used to serialize access to this data.
 */

static int
example_m_getstat(void *arg, uint_t stat, uint64_t *val)
{
	example_t *ep = arg;

	mutex_enter(&ep->ep_lock);
	switch (stat) {
	case MAC_STAT_RBYTES:
		*val = ep->ep_stats.eps_rbytes;
		break;
	case MAC_STAT_OBYTES:
		*val = ep->ep_stats.eps_obytes;
		break;
	case MAC_STAT_IPACKETS:
		*val = ep->ep_stats.eps_ipackets;
		break;
	case MAC_STAT_OPACKETS:
		*val = ep->ep_stats.eps_opackets;
		break;

	/*
	 * Note, there are many more stats that should be checked and
	 * filled in if supported. You should use one case statement for
	 * each stat.
	 */

	default:
		mutex_exit(&ep->ep_lock);
		return (ENOTSUP);
	}
	mutex_exit(&ep->ep_lock);

	return (0);
}

The device driver may return one of the following errors. While this list is not intended to be exhaustive, it is recommended to use one of these if possible.
The specified statistic is unknown, unsupported, or unimplemented.
A transport or DMA FM related error occurred while trying to sync data from the device.
The device is not currently in a state where it can currently service the request.

mac(9E), mac_register(9F), mac_register(9S)
May 31, 2016 OmniOS