[PATCH net-next v3 1/5] ionic: write the extra_stats invalid markers one counter at a time

[Eric Joyner <eric.joyner@amd.com>]

From: "Nikhil P. Rao" <nikhil.rao@amd.com>

ionic_port_init() marks every counter in the device-written extra_stats
block invalid before asking firmware to refresh it, so that a statistic
this driver knows about but the firmware does not is reported as absent
rather than as zero.  It does that with a memset() of the whole block.

The .get_fec_stats handler added later in this series reads those
counters one at a time and tests each against IONIC_STAT_INVALID to
decide whether to report it.  memset() gives no guarantee about the
width of its stores, so such a reader can observe a counter that is
neither its old value nor the marker.

The block is entirely __le64, each member naturally aligned, so walk it
as an array and write the markers one counter at a time instead.  A
counter read on its own is then either a complete value or the marker.

Signed-off-by: Nikhil P. Rao <nikhil.rao@amd.com>
Signed-off-by: Eric Joyner <eric.joyner@amd.com>
---
 drivers/net/ethernet/pensando/ionic/ionic_main.c  | 8 ++++++--
 drivers/net/ethernet/pensando/ionic/ionic_stats.h | 2 ++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_main.c b/drivers/net/ethernet/pensando/ionic/ionic_main.c
index 38b47b959a11..8197df5532f5 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_main.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_main.c
@@ -12,6 +12,7 @@
 #include "ionic.h"
 #include "ionic_bus.h"
 #include "ionic_lif.h"
+#include "ionic_stats.h"
 #include "ionic_debugfs.h"
 
 MODULE_DESCRIPTION(IONIC_DRV_DESCRIPTION);
@@ -723,7 +724,9 @@ int ionic_port_init(struct ionic *ionic)
 	struct ionic_identity *ident = &ionic->ident;
 	struct ionic_dev *idev = &ionic->idev;
 	bool allocated = false;
+	__le64 *stat;
 	size_t sz;
+	size_t i;
 	int err;
 
 	if (!idev->port_info) {
@@ -741,8 +744,9 @@ int ionic_port_init(struct ionic *ionic)
 	/* If the driver knows about more "extra stats" than the firmware,
 	 * make sure these stats are marked as invalid.
 	 */
-	memset(&idev->port_info->extra_stats, 0xff,
-	       sizeof(idev->port_info->extra_stats));
+	stat = (__le64 *)&idev->port_info->extra_stats;
+	for (i = 0; i < sizeof(idev->port_info->extra_stats) / sizeof(*stat); i++)
+		WRITE_ONCE(stat[i], IONIC_STAT_INVALID);
 
 	WRITE_ONCE(idev->link_down_count_init, false);
 
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_stats.h b/drivers/net/ethernet/pensando/ionic/ionic_stats.h
index 7ed935868e84..8a0edcc86fb8 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_stats.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_stats.h
@@ -4,6 +4,8 @@
 #ifndef _IONIC_STATS_H_
 #define _IONIC_STATS_H_
 
+#include <linux/ethtool.h>
+
 #define IONIC_STAT_INVALID	(cpu_to_le64(~0ULL))
 
 #define IONIC_STAT_TO_OFFSET(type, stat_name) (offsetof(type, stat_name))

-- 
2.53.0