nfp: protect each repr pointer individually with RCU

Representors are grouped in sets by type.  Currently the whole
sets are under RCU protection, but individual representor pointers
are not.  This causes some inconveniences when representors have
to be destroyed, because we have to allocate new sets to remove
any representors.  Protect the individual pointers with RCU.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 38 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c
index e2452176fa23..f67da6bde9da 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c
@@ -46,6 +46,13 @@
 #include "nfp_net_sriov.h"
 #include "nfp_port.h"
 
+struct net_device *
+nfp_repr_get_locked(struct nfp_app *app, struct nfp_reprs *set, unsigned int id)
+{
+	return rcu_dereference_protected(set->reprs[id],
+					 lockdep_is_held(&app->pf->lock));
+}
+
 static void
 nfp_repr_inc_tx_stats(struct net_device *netdev, unsigned int len,
 		      int tx_status)
@@ -369,21 +376,24 @@ static void nfp_repr_clean_and_free(struct nfp_repr *repr)
 	nfp_repr_free(repr);
 }
 
-void nfp_reprs_clean_and_free(struct nfp_reprs *reprs)
+void nfp_reprs_clean_and_free(struct nfp_app *app, struct nfp_reprs *reprs)
 {
+	struct net_device *netdev;
 	unsigned int i;
 
-	for (i = 0; i < reprs->num_reprs; i++)
-		if (reprs->reprs[i])
-			nfp_repr_clean_and_free(netdev_priv(reprs->reprs[i]));
+	for (i = 0; i < reprs->num_reprs; i++) {
+		netdev = nfp_repr_get_locked(app, reprs, i);
+		if (netdev)
+			nfp_repr_clean_and_free(netdev_priv(netdev));
+	}
 
 	kfree(reprs);
 }
 
 void
-nfp_reprs_clean_and_free_by_type(struct nfp_app *app,
-				 enum nfp_repr_type type)
+nfp_reprs_clean_and_free_by_type(struct nfp_app *app, enum nfp_repr_type type)
 {
+	struct net_device *netdev;
 	struct nfp_reprs *reprs;
 	int i;
 
@@ -395,14 +405,16 @@ nfp_reprs_clean_and_free_by_type(struct nfp_app *app,
 	/* Preclean must happen before we remove the reprs reference from the
 	 * app below.
 	 */
-	for (i = 0; i < reprs->num_reprs; i++)
-		if (reprs->reprs[i])
-			nfp_app_repr_preclean(app, reprs->reprs[i]);
+	for (i = 0; i < reprs->num_reprs; i++) {
+		netdev = nfp_repr_get_locked(app, reprs, i);
+		if (netdev)
+			nfp_app_repr_preclean(app, netdev);
+	}
 
 	reprs = nfp_app_reprs_set(app, type, NULL);
 
 	synchronize_rcu();
-	nfp_reprs_clean_and_free(reprs);
+	nfp_reprs_clean_and_free(app, reprs);
 }
 
 struct nfp_reprs *nfp_reprs_alloc(unsigned int num_reprs)
@@ -420,46 +432,29 @@ struct nfp_reprs *nfp_reprs_alloc(unsigned int num_reprs)
 
 int nfp_reprs_resync_phys_ports(struct nfp_app *app)
 {
-	struct nfp_reprs *reprs, *old_reprs;
+	struct net_device *netdev;
+	struct nfp_reprs *reprs;
 	struct nfp_repr *repr;
 	int i;
 
-	old_reprs = nfp_reprs_get_locked(app, NFP_REPR_TYPE_PHYS_PORT);
-	if (!old_reprs)
-		return 0;
-
-	reprs = nfp_reprs_alloc(old_reprs->num_reprs);
+	reprs = nfp_reprs_get_locked(app, NFP_REPR_TYPE_PHYS_PORT);
 	if (!reprs)
-		return -ENOMEM;
-
-	for (i = 0; i < old_reprs->num_reprs; i++) {
-		if (!old_reprs->reprs[i])
-			continue;
-
-		repr = netdev_priv(old_reprs->reprs[i]);
-		if (repr->port->type == NFP_PORT_INVALID) {
-			nfp_app_repr_preclean(app, old_reprs->reprs[i]);
-			continue;
-		}
-
-		reprs->reprs[i] = old_reprs->reprs[i];
-	}
-
-	old_reprs = nfp_app_reprs_set(app, NFP_REPR_TYPE_PHYS_PORT, reprs);
-	synchronize_rcu();
+		return 0;
 
-	/* Now we free up removed representors */
-	for (i = 0; i < old_reprs->num_reprs; i++) {
-		if (!old_reprs->reprs[i])
+	for (i = 0; i < reprs->num_reprs; i++) {
+		netdev = nfp_repr_get_locked(app, reprs, i);
+		if (!netdev)
 			continue;
 
-		repr = netdev_priv(old_reprs->reprs[i]);
+		repr = netdev_priv(netdev);
 		if (repr->port->type != NFP_PORT_INVALID)
 			continue;
 
+		nfp_app_repr_preclean(app, netdev);
+		rcu_assign_pointer(reprs->reprs[i], NULL);
+		synchronize_rcu();
 		nfp_repr_clean(repr);
 	}
 
-	kfree(old_reprs);
 	return 0;
 }