IB/mlx4: Alias GUID adding persistency support

If the SM rejects an alias GUID request the PF driver keeps trying to acquire
the specified GUID indefinitely, utilizing an exponential backoff scheme.

Retrying is managed per GUID entry. Each entry that wasn't applied holds its
next retry information. Retry requests to the SM consist of records of 8
consecutive GUIDS. Each record that contains GUIDs requiring retries holds its
next time-to-run based on the retry information of all its GUID entries. The
record having the lowest retry time will run first when that retry time
arrives.

Since the method (SET or DELETE) as sent to the SM applies to all the GUIDs in
the record, we must handle SET requests and DELETE requests in separate SM
messages (one for SETs and the other for DELETEs).

To avoid race conditions where a GUID entry request (set or delete) was
modified after the SM request was sent, we save the method and the requested
indices as part of the callback's context -- thus, only the requested indexes
are evaluated when the response is received.

When an GUID entry is approved we turn off its retry-required bit, this
prevents redundant SM retries from occurring on that record.

The port down event should be sent only when previously it was up. Likewise,
the port up event should be sent only if previously the port was down.

Synchronization was added around the flows that change entries and record state
to prevent race conditions.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx4/mlx4_ib.h

@@ -342,7 +342,6 @@ struct mlx4_ib_ah {
 enum mlx4_guid_alias_rec_status {
 	MLX4_GUID_INFO_STATUS_IDLE,
 	MLX4_GUID_INFO_STATUS_SET,
-	MLX4_GUID_INFO_STATUS_PENDING,
 };
 
 enum mlx4_guid_alias_rec_ownership {
@@ -360,8 +359,9 @@ struct mlx4_sriov_alias_guid_info_rec_det {
 	u8 all_recs[GUID_REC_SIZE * NUM_ALIAS_GUID_IN_REC];
 	ib_sa_comp_mask guid_indexes; /*indicates what from the 8 records are valid*/
 	enum mlx4_guid_alias_rec_status status; /*indicates the administraively status of the record.*/
-	u8 method; /*set or delete*/
 	enum mlx4_guid_alias_rec_ownership ownership; /*indicates who assign that alias_guid record*/
+	unsigned int guids_retry_schedule[NUM_ALIAS_GUID_IN_REC];
+	u64 time_to_run;
 };
 
 struct mlx4_sriov_alias_guid_port_rec_det {

drivers/infiniband/hw/mlx4/sysfs.c

@@ -80,6 +80,7 @@ static ssize_t store_admin_alias_guid(struct device *dev,
 	struct mlx4_ib_iov_port *port = mlx4_ib_iov_dentry->ctx;
 	struct mlx4_ib_dev *mdev = port->dev;
 	u64 sysadmin_ag_val;
+	unsigned long flags;
 
 	record_num = mlx4_ib_iov_dentry->entry_num / 8;
 	guid_index_in_rec = mlx4_ib_iov_dentry->entry_num % 8;
@@ -87,6 +88,7 @@ static ssize_t store_admin_alias_guid(struct device *dev,
 		pr_err("GUID 0 block 0 is RO\n");
 		return count;
 	}
+	spin_lock_irqsave(&mdev->sriov.alias_guid.ag_work_lock, flags);
 	sscanf(buf, "%llx", &sysadmin_ag_val);
 	*(__be64 *)&mdev->sriov.alias_guid.ports_guid[port->num - 1].
 		all_rec_per_port[record_num].
@@ -96,14 +98,8 @@ static ssize_t store_admin_alias_guid(struct device *dev,
 	/* Change the state to be pending for update */
 	mdev->sriov.alias_guid.ports_guid[port->num - 1].all_rec_per_port[record_num].status
 		= MLX4_GUID_INFO_STATUS_IDLE ;
-
-	mdev->sriov.alias_guid.ports_guid[port->num - 1].all_rec_per_port[record_num].method
-		= MLX4_GUID_INFO_RECORD_SET;
-
 	switch (sysadmin_ag_val) {
 	case MLX4_GUID_FOR_DELETE_VAL:
-		mdev->sriov.alias_guid.ports_guid[port->num - 1].all_rec_per_port[record_num].method
-			= MLX4_GUID_INFO_RECORD_DELETE;
 		mdev->sriov.alias_guid.ports_guid[port->num - 1].all_rec_per_port[record_num].ownership
 			= MLX4_GUID_SYSADMIN_ASSIGN;
 		break;
@@ -121,8 +117,9 @@ static ssize_t store_admin_alias_guid(struct device *dev,
 
 	/* set the record index */
 	mdev->sriov.alias_guid.ports_guid[port->num - 1].all_rec_per_port[record_num].guid_indexes
-		= mlx4_ib_get_aguid_comp_mask_from_ix(guid_index_in_rec);
+		|= mlx4_ib_get_aguid_comp_mask_from_ix(guid_index_in_rec);
 
+	spin_unlock_irqrestore(&mdev->sriov.alias_guid.ag_work_lock, flags);
 	mlx4_ib_init_alias_guid_work(mdev, port->num - 1);
 
 	return count;