Due to checksum offloading one more element could be written to the ring

than there is space available.
ok dlg

diff --git a/sys/dev/pci/if_igc.c b/sys/dev/pci/if_igc.c
index 734bc8b..a904d43 100644 (file)
--- a/sys/dev/pci/if_igc.c
+++ b/sys/dev/pci/if_igc.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_igc.c,v 1.9 2022/06/02 07:41:17 mbuhl Exp $        */
+/*     $OpenBSD: if_igc.c,v 1.10 2022/11/11 16:41:44 mbuhl Exp $       */
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
@@ -978,7 +978,7 @@ igc_start(struct ifqueue *ifq)
        mask = sc->num_tx_desc - 1;
 
        for (;;) {
-               if (free <= IGC_MAX_SCATTER) {
+               if (free <= IGC_MAX_SCATTER + 1) {
                        ifq_set_oactive(ifq);
                        break;
                }
@@ -1005,6 +1005,7 @@ igc_start(struct ifqueue *ifq)
                        /* Consume the first descriptor */
                        prod++;
                        prod &= mask;
+                       free--;
                }
 
                for (i = 0; i < map->dm_nsegs; i++) {