[PATCH for-next v3] IB/core: Only update PKEY and GID caches on respective events

[Håkon Bugge <haakon.bugge@xxxxxxxxxx>]

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.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>

---

v1 -> v2:
   * Changed signature of ib_cache_update() as per Leon's suggestion
   * Added Fixes tag as per Zhu Yanjun' suggestion

v2 -> v3:
   * Rebased on tip of dledford/wip/jgg-for-next, 331859d320f5
     ("RDMA/hns: Remove unused CMDQ member")
   * Added Leon's r-b
---
 drivers/infiniband/core/cache.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 3b0991f..d320459 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -1465,10 +1465,12 @@ static int config_non_roce_gid_cache(struct ib_device *device,
 }
 
 static int
-ib_cache_update(struct ib_device *device, u32 port, bool enforce_security)
+ib_cache_update(struct ib_device *device, u32 port, bool update_gids,
+		bool update_pkeys, 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;
 	int                        i;
 	int                        ret;
 
@@ -1485,14 +1487,16 @@ 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_gids) {
 		ret = config_non_roce_gid_cache(device, port,
 						tprops->gid_tbl_len);
 		if (ret)
 			goto err;
 	}
 
-	if (tprops->pkey_tbl_len) {
+	update_pkeys &= !!tprops->pkey_tbl_len;
+
+	if (update_pkeys) {
 		pkey_cache = kmalloc(struct_size(pkey_cache, table,
 						 tprops->pkey_tbl_len),
 				     GFP_KERNEL);
@@ -1517,9 +1521,10 @@ 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_pkeys) {
+		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;
 
@@ -1551,6 +1556,8 @@ 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->event.event == IB_EVENT_GID_CHANGE,
+			      work->event.event == IB_EVENT_PKEY_CHANGE,
 			      work->enforce_security);
 
 	/* GID event is notified already for individual GID entries by
@@ -1624,7 +1631,7 @@ 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, true, true, true);
 		if (err)
 			return err;
 	}
-- 
1.8.3.1