Reorder checks for I210/I350 chips so that we don't remove the last 4 bytes

of the packet if they happen to be split across an mbuf boundary, as these
always strip the CRC before the driver sees it.

all the hard work figuring out what was happening done by dtucker@
tested on I210 by dtucker@ and kevlo@, on I350 by me and hrvoje
ok kevlo@ stsp@

Author: jmatthew

sys/dev/pci/if_em.c

@@ -31,7 +31,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 ***************************************************************************/
 
-/* $OpenBSD: if_em.c,v 1.378 2024/08/31 16:23:09 deraadt Exp $ */
+/* $OpenBSD: if_em.c,v 1.379 2025/07/14 11:52:43 jmatthew Exp $ */
 /* $FreeBSD: if_em.c,v 1.46 2004/09/29 18:28:28 mlaier Exp $ */
 
 #include <dev/pci/if_em.h>
@@ -3116,13 +3116,14 @@ em_rxeof(struct em_queue *que)
 
 		if (status & E1000_RXD_STAT_EOP) {
 			eop = 1;
-			if (desc_len < ETHER_CRC_LEN) {
+			if (sc->hw.mac_type == em_i210 ||
+			    sc->hw.mac_type == em_i350) {
+				/* crc has already been stripped */
+				len = desc_len;
+			} else if (desc_len < ETHER_CRC_LEN) {
 				len = 0;
 				prev_len_adj = ETHER_CRC_LEN - desc_len;
-			} else if (sc->hw.mac_type == em_i210 ||
-			    sc->hw.mac_type == em_i350)
-				len = desc_len;
-			else
+			} else
 				len = desc_len - ETHER_CRC_LEN;
 		} else {
 			eop = 0;