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Date:      Sun, 3 Jan 2016 21:32:47 +0000 (UTC)
From:      Andriy Voskoboinyk <avos@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r293119 - head/sys/dev/iwm
Message-ID:  <201601032132.u03LWlia053658@repo.freebsd.org>
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Author: avos
Date: Sun Jan  3 21:32:47 2016
New Revision: 293119
URL: https://svnweb.freebsd.org/changeset/base/293119

Log:
  iwm: use m_collapse() to defragment a mbuf chain
  
  - Simplify defragmentation code.
  - Use proper number of dma segments for data.
  
  Approved by:	adrian (mentor)
  Obtained from:	DragonFlyBSD (mostly)
  Differential Revision:	https://reviews.freebsd.org/D4754

Modified:
  head/sys/dev/iwm/if_iwm.c

Modified: head/sys/dev/iwm/if_iwm.c
==============================================================================
--- head/sys/dev/iwm/if_iwm.c	Sun Jan  3 21:30:22 2016	(r293118)
+++ head/sys/dev/iwm/if_iwm.c	Sun Jan  3 21:32:47 2016	(r293119)
@@ -956,7 +956,7 @@ iwm_alloc_tx_ring(struct iwm_softc *sc, 
 
 	error = bus_dma_tag_create(sc->sc_dmat, 1, 0,
 	    BUS_SPACE_MAXADDR_32BIT, BUS_SPACE_MAXADDR, NULL, NULL, MCLBYTES,
-            IWM_MAX_SCATTER - 1, MCLBYTES, 0, NULL, NULL, &ring->data_dmat);
+            IWM_MAX_SCATTER - 2, MCLBYTES, 0, NULL, NULL, &ring->data_dmat);
 	if (error != 0) {
 		device_printf(sc->sc_dev, "could not create TX buf DMA tag\n");
 		goto fail;
@@ -2778,23 +2778,15 @@ iwm_tx(struct iwm_softc *sc, struct mbuf
 			return error;
 		}
 		/* Too many DMA segments, linearize mbuf. */
-		MGETHDR(m1, M_NOWAIT, MT_DATA);
+		m1 = m_collapse(m, M_NOWAIT, IWM_MAX_SCATTER - 2);
 		if (m1 == NULL) {
+			device_printf(sc->sc_dev,
+			    "%s: could not defrag mbuf\n", __func__);
 			m_freem(m);
-			return ENOBUFS;
-		}
-		if (m->m_pkthdr.len > MHLEN) {
-			MCLGET(m1, M_NOWAIT);
-			if (!(m1->m_flags & M_EXT)) {
-				m_freem(m);
-				m_freem(m1);
-				return ENOBUFS;
-			}
+			return (ENOBUFS);
 		}
-		m_copydata(m, 0, m->m_pkthdr.len, mtod(m1, void *));
-		m1->m_pkthdr.len = m1->m_len = m->m_pkthdr.len;
-		m_freem(m);
 		m = m1;
+
 		error = bus_dmamap_load_mbuf_sg(ring->data_dmat, data->map, m,
 		    segs, &nsegs, BUS_DMA_NOWAIT);
 		if (error != 0) {

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