Change m_devget()'s outdated and unused `offset' argument to actually mean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, 1 insertions, 4 deletions

diff --git a/sys/dev/vx/if_vx.c b/sys/dev/vx/if_vx.c
index e1fa760..f475080 100644
--- a/sys/dev/vx/if_vx.c
+++ b/sys/dev/vx/if_vx.c
@@ -691,15 +691,12 @@ again:
     {
 	struct mbuf		*m0;
 
-	m0 = m_devget(mtod(m, char *) - ETHER_ALIGN,
-	    m->m_pkthdr.len + ETHER_ALIGN, 0, ifp, NULL);
-
+	m0 = m_devget(mtod(m, char *), m->m_pkthdr.len, ETHER_ALIGN, ifp, NULL);
 	if (m0 == NULL) {
 		ifp->if_ierrors++;
 		goto abort;
 	}
 
-	m_adj(m0, ETHER_ALIGN);
 	m_freem(m);
 	m = m0;
     }