[PATCH for-next] IB/core: Only update PKEY and GID caches on respective events

["Håkon Bugge" <haakon.bugge@oracle.com>]

Both the PKEY and GID tables in an HCA can hold in the order of
hundreds entries. Reading them are expensive. Partly because the API
for retrieving them only returns a single entry at a time. Further, on
certain implementations, e.g., CX-3, the VFs are paravirtualized in
this respect and have to rely on the PF driver to perform the
read. This again demands VF to PF communication.

IB Core's cache is refreshed on all events. Hence, filter the refresh
of the PKEY and GID caches based on the event received being
IB_EVENT_PKEY_CHANGE and IB_EVENT_GID_CHANGE respectively.

Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
---
 drivers/infiniband/core/cache.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 5c9fac7..531ae6b 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -1472,10 +1472,14 @@ static int config_non_roce_gid_cache(struct ib_device *device,
 }
 
 static int
-ib_cache_update(struct ib_device *device, u8 port, bool enforce_security)
+ib_cache_update(struct ib_device *device, u8 port, enum ib_event_type event,
+		bool reg_dev, bool enforce_security)
 {
 	struct ib_port_attr       *tprops = NULL;
-	struct ib_pkey_cache      *pkey_cache = NULL, *old_pkey_cache;
+	struct ib_pkey_cache      *pkey_cache = NULL;
+	struct ib_pkey_cache      *old_pkey_cache = NULL;
+	bool			   update_pkey_cache = (reg_dev || event == IB_EVENT_PKEY_CHANGE);
+	bool			   update_gid_cache = (reg_dev || event == IB_EVENT_GID_CHANGE);
 	int                        i;
 	int                        ret;
 
@@ -1492,14 +1496,16 @@ static int config_non_roce_gid_cache(struct ib_device *device,
 		goto err;
 	}
 
-	if (!rdma_protocol_roce(device, port)) {
+	if (!rdma_protocol_roce(device, port) && update_gid_cache) {
 		ret = config_non_roce_gid_cache(device, port,
 						tprops->gid_tbl_len);
 		if (ret)
 			goto err;
 	}
 
-	if (tprops->pkey_tbl_len) {
+	update_pkey_cache &= !!tprops->pkey_tbl_len;
+
+	if (update_pkey_cache) {
 		pkey_cache = kmalloc(struct_size(pkey_cache, table,
 						 tprops->pkey_tbl_len),
 				     GFP_KERNEL);
@@ -1524,9 +1530,10 @@ static int config_non_roce_gid_cache(struct ib_device *device,
 
 	write_lock_irq(&device->cache_lock);
 
-	old_pkey_cache = device->port_data[port].cache.pkey;
-
-	device->port_data[port].cache.pkey = pkey_cache;
+	if (update_pkey_cache) {
+		old_pkey_cache = device->port_data[port].cache.pkey;
+		device->port_data[port].cache.pkey = pkey_cache;
+	}
 	device->port_data[port].cache.lmc = tprops->lmc;
 	device->port_data[port].cache.port_state = tprops->state;
 
@@ -1558,7 +1565,7 @@ static void ib_cache_event_task(struct work_struct *_work)
 	 * the cache.
 	 */
 	ret = ib_cache_update(work->event.device, work->event.element.port_num,
-			      work->enforce_security);
+			      work->event.event, false, work->enforce_security);
 
 	/* GID event is notified already for individual GID entries by
 	 * dispatch_gid_change_event(). Hence, notifiy for rest of the
@@ -1631,7 +1638,7 @@ int ib_cache_setup_one(struct ib_device *device)
 		return err;
 
 	rdma_for_each_port (device, p) {
-		err = ib_cache_update(device, p, true);
+		err = ib_cache_update(device, p, 0, true, true);
 		if (err)
 			return err;
 	}
-- 
1.8.3.1