nfp: add nfp_reprs_get_locked() helper

The write side of repr tables is always done under pf->lock.
Add a helper to dereference repr table pointers under protection
of that lock.

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>

drivers/net/ethernet/netronome/nfp/nfp_app.c

@@ -32,6 +32,8 @@
  */
 
 #include <linux/bug.h>
+#include <linux/lockdep.h>
+#include <linux/rcupdate.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 
@@ -98,14 +100,20 @@ nfp_app_ctrl_msg_alloc(struct nfp_app *app, unsigned int size, gfp_t priority)
 	return skb;
 }
 
+struct nfp_reprs *
+nfp_reprs_get_locked(struct nfp_app *app, enum nfp_repr_type type)
+{
+	return rcu_dereference_protected(app->reprs[type],
+					 lockdep_is_held(&app->pf->lock));
+}
+
 struct nfp_reprs *
 nfp_app_reprs_set(struct nfp_app *app, enum nfp_repr_type type,
 		  struct nfp_reprs *reprs)
 {
 	struct nfp_reprs *old;
 
-	old = rcu_dereference_protected(app->reprs[type],
-					lockdep_is_held(&app->pf->lock));
+	old = nfp_reprs_get_locked(app, type);
 	rcu_assign_pointer(app->reprs[type], reprs);
 
 	return old;

drivers/net/ethernet/netronome/nfp/nfp_app.h

@@ -384,6 +384,8 @@ static inline struct net_device *nfp_app_repr_get(struct nfp_app *app, u32 id)
 
 struct nfp_app *nfp_app_from_netdev(struct net_device *netdev);
 
+struct nfp_reprs *
+nfp_reprs_get_locked(struct nfp_app *app, enum nfp_repr_type type);
 struct nfp_reprs *
 nfp_app_reprs_set(struct nfp_app *app, enum nfp_repr_type type,
 		  struct nfp_reprs *reprs);

drivers/net/ethernet/netronome/nfp/nfp_net_repr.c

@@ -424,9 +424,7 @@ int nfp_reprs_resync_phys_ports(struct nfp_app *app)
 	struct nfp_repr *repr;
 	int i;
 
-	old_reprs =
-		rcu_dereference_protected(app->reprs[NFP_REPR_TYPE_PHYS_PORT],
-					  lockdep_is_held(&app->pf->lock));
+	old_reprs = nfp_reprs_get_locked(app, NFP_REPR_TYPE_PHYS_PORT);
 	if (!old_reprs)
 		return 0;