Change m_devget()'s outdated and unused `offset' argument to actually mean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_wb.c b/sys/pci/if_wb.c
index 50de1fd..a03951b 100644
--- a/sys/pci/if_wb.c
+++ b/sys/pci/if_wb.c
@@ -1175,14 +1175,13 @@ static void wb_rxeof(sc)
 		 */
 		total_len -= ETHER_CRC_LEN;
 
-		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);
 		wb_newbuf(sc, cur_rx, m);
 		if (m0 == NULL) {
 			ifp->if_ierrors++;
 			break;
 		}
-		m_adj(m0, ETHER_ALIGN);
 		m = m0;
 
 		ifp->if_ipackets++;