Change m_devget()'s outdated and unused `offset' argument to actually mean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

7 files changed, 13 insertions, 22 deletions

diff --git a/sys/dev/dc/if_dc.c b/sys/dev/dc/if_dc.c
index 83eb65e..0ef88c3 100644
--- a/sys/dev/dc/if_dc.c
+++ b/sys/dev/dc/if_dc.c
@@ -2502,15 +2502,14 @@ static void dc_rxeof(sc)
 		/* No errors; receive the packet. */	
 		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);
 		dc_newbuf(sc, i, m);
 		DC_INC(i, DC_RX_LIST_CNT);
 		if (m0 == NULL) {
 			ifp->if_ierrors++;
 			continue;
 		}
-		m_adj(m0, ETHER_ALIGN);
 		m = m0;
 
 		ifp->if_ipackets++;
diff --git a/sys/dev/lge/if_lge.c b/sys/dev/lge/if_lge.c
index d6f9e80..1558004 100644
--- a/sys/dev/lge/if_lge.c
+++ b/sys/dev/lge/if_lge.c
@@ -993,8 +993,8 @@ static void lge_rxeof(sc, cnt)
 		}
 
 		if (lge_newbuf(sc, &LGE_RXTAIL(sc), NULL) == ENOBUFS) {
-			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);
 			lge_newbuf(sc, &LGE_RXTAIL(sc), m);
 			if (m0 == NULL) {
 				printf("lge%d: no receive buffers "
@@ -1003,7 +1003,6 @@ static void lge_rxeof(sc, cnt)
 				ifp->if_ierrors++;
 				continue;
 			}
-			m_adj(m0, ETHER_ALIGN);
 			m = m0;
 		} else {
 			m->m_pkthdr.rcvif = ifp;
diff --git a/sys/dev/nge/if_nge.c b/sys/dev/nge/if_nge.c
index 9c15beb..65dd718 100644
--- a/sys/dev/nge/if_nge.c
+++ b/sys/dev/nge/if_nge.c
@@ -1278,8 +1278,8 @@ static void nge_rxeof(sc)
 		 * only gigE chip I know of with alignment constraints
 		 * on receive buffers. RX buffers must be 64-bit aligned.
 		 */
-		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);
 		nge_newbuf(sc, cur_rx, m);
 		if (m0 == NULL) {
 			printf("nge%d: no receive buffers "
@@ -1288,7 +1288,6 @@ static void nge_rxeof(sc)
 			ifp->if_ierrors++;
 			continue;
 		}
-		m_adj(m0, ETHER_ALIGN);
 		m = m0;
 
 		ifp->if_ipackets++;
diff --git a/sys/dev/sf/if_sf.c b/sys/dev/sf/if_sf.c
index dd26fca..e0d0149 100644
--- a/sys/dev/sf/if_sf.c
+++ b/sys/dev/sf/if_sf.c
@@ -989,14 +989,13 @@ static void sf_rxeof(sc)
 			continue;
 		}
 
-		m0 = m_devget(mtod(m, char *) - ETHER_ALIGN,
-		    cur_rx->sf_len + ETHER_ALIGN, 0, ifp, NULL);
+		m0 = m_devget(mtod(m, char *), cur_rx->sf_len, ETHER_ALIGN,
+		    ifp, NULL);
 		sf_newbuf(sc, desc, m);
 		if (m0 == NULL) {
 			ifp->if_ierrors++;
 			continue;
 		}
-		m_adj(m0, ETHER_ALIGN);
 		m = m0;
 
 		eh = mtod(m, struct ether_header *);
diff --git a/sys/dev/sk/if_sk.c b/sys/dev/sk/if_sk.c
index 83d5720..6c9ec6a 100644
--- a/sys/dev/sk/if_sk.c
+++ b/sys/dev/sk/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;
diff --git a/sys/dev/vr/if_vr.c b/sys/dev/vr/if_vr.c
index 93fba3e..9ed0266 100644
--- a/sys/dev/vr/if_vr.c
+++ b/sys/dev/vr/if_vr.c
@@ -1029,14 +1029,13 @@ static void vr_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);
 		vr_newbuf(sc, cur_rx, m);
 		if (m0 == NULL) {
 			ifp->if_ierrors++;
 			continue;
 		}
-		m_adj(m0, ETHER_ALIGN);
 		m = m0;
 
 		ifp->if_ipackets++;
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;
     }