IB/core: Implement clear counters

This patch adds sysfs clear counter interface to clear the counters.

Reviewers-notes:
  Please note that there is a possible race between clearing and
  updating the counter values on architectures that do not write
  64-bit atomically.

Orabug: 26761264
MlnxSF: 00384047
Upstream_status: ignore
Signed-off-by: Parav Pandit <[email protected]>
Signed-off-by: Aron Silverton <[email protected]>
Reviewed-by: Håkon Bugge <[email protected]>

Signed-off-by: Somasundaram Krishnasamy <[email protected]>

Author: paravmellanox

drivers/infiniband/core/sysfs.c

@@ -909,6 +909,70 @@ static struct attribute *alloc_hsa_lifespan(char *name, u8 port_num)
 	return &hsa->attr;
 }
 
+static void clear_cached_hw_stats(struct rdma_hw_stats *stats)
+{
+	int i;
+
+	for (i = 0; i < stats->num_counters; i++)
+		stats->value[i] = 0;
+}
+
+static ssize_t set_clear_hw_stats(struct kobject *kobj,
+			      struct attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct hw_stats_attribute *hsa;
+	struct rdma_hw_stats *stats;
+	struct ib_device *dev;
+	struct ib_port *port;
+	int ret;
+
+	hsa = container_of(attr, struct hw_stats_attribute, attr);
+	if (!hsa->port_num) {
+		dev = container_of((struct device *)kobj,
+				   struct ib_device, dev);
+		stats = dev->hw_stats;
+	} else {
+		port = container_of(kobj, struct ib_port, kobj);
+		dev = port->ibdev;
+		stats = port->hw_stats;
+	}
+	if (dev->clear_hw_stats) {
+		ret = dev->clear_hw_stats(dev, hsa->port_num);
+		clear_cached_hw_stats(stats);
+	} else {
+		return -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t show_clear_hw_stats(struct kobject *kobj, struct attribute *attr,
+				   char *buf)
+{
+	return sprintf(buf, "%d\n", 0);
+}
+
+static struct attribute *alloc_hsa_clear_stats(char *name, u8 port_num)
+{
+	struct hw_stats_attribute *hsa;
+
+	hsa = kmalloc(sizeof(*hsa), GFP_KERNEL);
+	if (!hsa)
+		return NULL;
+
+	hsa->attr.name = name;
+	hsa->attr.mode = S_IWUSR | S_IRUSR;
+	hsa->store = set_clear_hw_stats;
+	hsa->show = show_clear_hw_stats;
+	hsa->index = 0;
+	hsa->port_num = port_num;
+
+	return &hsa->attr;
+}
+
 static void setup_hw_stats(struct ib_device *device, struct ib_port *port,
 			   u8 port_num)
 {
@@ -929,7 +993,7 @@ static void setup_hw_stats(struct ib_device *device, struct ib_port *port,
 	 * one to NULL terminate the list for the sysfs core code
 	 */
 	hsag = kzalloc(sizeof(*hsag) +
-		       sizeof(void *) * (stats->num_counters + 2),
+		       sizeof(void *) * (stats->num_counters + 3),
 		       GFP_KERNEL);
 	if (!hsag)
 		goto err_free_stats;
@@ -956,6 +1020,11 @@ static void setup_hw_stats(struct ib_device *device, struct ib_port *port,
 	if (hsag->attrs[i])
 		sysfs_attr_init(hsag->attrs[i]);
 
+	i++;
+	hsag->attrs[i] = alloc_hsa_clear_stats("clear_counters", port_num);
+	if (hsag->attrs[i])
+		sysfs_attr_init(hsag->attrs[i]);
+
 	if (port) {
 		struct kobject *kobj = &port->kobj;
 		ret = sysfs_create_group(kobj, hsag);

include/rdma/ib_verbs.h

@@ -2097,6 +2097,13 @@ struct ib_device {
 	int		           (*get_hw_stats)(struct ib_device *device,
 						   struct rdma_hw_stats *stats,
 						   u8 port, int index);
+	/**
+	 * clear_hw_stats - Clear the hw stats
+	 * @ib_device - device whose counters to clear.
+	 * @port - port whose counters to clear.
+	 */
+	int		           (*clear_hw_stats)(struct ib_device *device,
+						     u8 port);
 	int		           (*query_device)(struct ib_device *device,
 						   struct ib_device_attr *device_attr,
 						   struct ib_udata *udata);