Change m_devget()'s outdated and unused `offset' argument to actually mean

something: offset into the first mbuf of the target chain before copying
the source data over.

Make drivers using m_devget() with a first argument "data - ETHER_ALIGN"
to use the offset argument to pass ETHER_ALIGN in. The way it was previously
done is potentially dangerous if the source data was at the top of a page
and the offset caused the previous page to be copied (if the
previous page has not yet been appropriately mapped).

The old `offset' argument in m_devget() is not used anywhere (it's always
0) and dates back to ~1995 (and earlier?) when support for ethernet trailers
existed. With that support gone, it was merely collecting dust.

Tested on alpha by: jlemon
Partially submitted by: jlemon
Reviewed by: jlemon
MFC after: 3 weeks

1 files changed, 2 insertions, 3 deletions

diff --git a/sys/pci/if_sk.c b/sys/pci/if_sk.c
index 83d5720..6c9ec6a 100644
--- a/sys/pci/if_sk.c
+++ b/sys/pci/if_sk.c
@@ -1579,8 +1579,8 @@ static void sk_rxeof(sc_if)
 		 */
 		if (sk_newbuf(sc_if, cur_rx, NULL) == ENOBUFS) {
 			struct mbuf		*m0;
-			m0 = m_devget(mtod(m, char *) - ETHER_ALIGN,
-			    total_len + ETHER_ALIGN, 0, ifp, NULL);
+			m0 = m_devget(mtod(m, char *), total_len, ETHER_ALIGN,
+			    ifp, NULL);
 			sk_newbuf(sc_if, cur_rx, m);
 			if (m0 == NULL) {
 				printf("sk%d: no receive buffers "
@@ -1589,7 +1589,6 @@ static void sk_rxeof(sc_if)
 				ifp->if_ierrors++;
 				continue;
 			}
-			m_adj(m0, ETHER_ALIGN);
 			m = m0;
 		} else {
 			m->m_pkthdr.rcvif = ifp;