netmap: get rid of save_if_input for emulated adapters

The save_if_input function pointer was meant to save the previous
value of ifp->if_input before replacing it with the emulated
adapter hook.
However, the same pointer value is already stored in the if_input
field of the netmap_adapter struct, to be used for host TX ring processing.

Reuse the netmap_adapter if_input field to simplify the code
and save some space.

MFC after:	14 days

(cherry picked from commit 6c9fe357435db6408ec6b01221b9ff9e7e9b0ff1)

2 files changed, 2 insertions, 21 deletions

diff --git a/sys/dev/netmap/netmap_freebsd.c b/sys/dev/netmap/netmap_freebsd.c
index b9055d589df1..19708406dc93 100644
--- a/sys/dev/netmap/netmap_freebsd.c
+++ b/sys/dev/netmap/netmap_freebsd.c
@@ -327,9 +327,7 @@ freebsd_generic_rx_handler(struct ifnet *ifp, struct mbuf *m)
 
 	stolen = generic_rx_handler(ifp, m);
 	if (!stolen) {
-		struct netmap_generic_adapter *gna =
-				(struct netmap_generic_adapter *)NA(ifp);
-		gna->save_if_input(ifp, m);
+		NA(ifp)->if_input(ifp, m);
 	}
 }
 
@@ -346,24 +344,10 @@ nm_os_catch_rx(struct netmap_generic_adapter *gna, int intercept)
 
 	nm_os_ifnet_lock();
 	if (intercept) {
-		if (gna->save_if_input) {
-			nm_prerr("RX on %s already intercepted", na->name);
-			ret = EBUSY; /* already set */
-			goto out;
-		}
-		gna->save_if_input = ifp->if_input;
 		ifp->if_input = freebsd_generic_rx_handler;
 	} else {
-		if (!gna->save_if_input) {
-			nm_prerr("Failed to undo RX intercept on %s",
-				na->name);
-			ret = EINVAL;  /* not saved */
-			goto out;
-		}
-		ifp->if_input = gna->save_if_input;
-		gna->save_if_input = NULL;
+		ifp->if_input = na->if_input;
 	}
-out:
 	nm_os_ifnet_unlock();
 
 	return ret;
diff --git a/sys/dev/netmap/netmap_kern.h b/sys/dev/netmap/netmap_kern.h
index 195b5de7a502..237b2b39047a 100644
--- a/sys/dev/netmap/netmap_kern.h
+++ b/sys/dev/netmap/netmap_kern.h
@@ -987,11 +987,8 @@ struct netmap_generic_adapter {	/* emulated device */
 	struct netmap_adapter *prev;
 
 	/* Emulated netmap adapters support:
-	 *  - save_if_input saves the if_input hook (FreeBSD);
 	 *  - mit implements rx interrupt mitigation;
 	 */
-	void (*save_if_input)(struct ifnet *, struct mbuf *);
-
 	struct nm_generic_mit *mit;
 #ifdef linux
         netdev_tx_t (*save_start_xmit)(struct mbuf *, struct ifnet *);