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From: Adrian Chadd <adrian@FreeBSD.org>
Date: Thu, 8 Jul 2010 14:59:32 +0000 (UTC)
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Subject: svn commit: r209807 - head/sys/mips/atheros
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Author: adrian
Date: Thu Jul  8 14:59:32 2010
New Revision: 209807
URL: http://svn.freebsd.org/changeset/base/209807

Log:
  Address PR kern/148307 - fix if_ath TX mbuf alignment/size constraint checks
  
  The existing code only checked the alignment of the first mbuf and
  didn't enforce the size constraints.
  
  This commit introduces a simple function to check the alignment and
  size of all mbufs in the list. This fixes the initial issue in the
  PR.
  
  PR: kern/148307
  Reviewed by: gonzo@

Modified:
  head/sys/mips/atheros/if_arge.c

Modified: head/sys/mips/atheros/if_arge.c
==============================================================================
--- head/sys/mips/atheros/if_arge.c	Thu Jul  8 14:56:42 2010	(r209806)
+++ head/sys/mips/atheros/if_arge.c	Thu Jul  8 14:59:32 2010	(r209807)
@@ -834,6 +834,28 @@ arge_init_locked(struct arge_softc *sc)
 }
 
 /*
+ * Return whether the mbuf chain is correctly aligned
+ * for the arge TX engine.
+ *
+ * The TX engine requires each fragment to be aligned to a
+ * 4 byte boundary and the size of each fragment except
+ * the last to be a multiple of 4 bytes.
+ */
+static int
+arge_mbuf_chain_is_tx_aligned(struct mbuf *m0)
+{
+	struct mbuf *m;
+
+	for (m = m0; m != NULL; m = m->m_next) {
+		if((mtod(m, intptr_t) & 3) != 0)
+			return 0;
+		if ((m->m_next != NULL) && ((m->m_len & 0x03) != 0))
+			return 0;
+	}
+	return 1;
+}
+
+/*
  * Encapsulate an mbuf chain in a descriptor by coupling the mbuf data
  * pointers to the fragment pointers.
  */
@@ -853,7 +875,7 @@ arge_encap(struct arge_softc *sc, struct
 	 * even 4 bytes
 	 */
 	m = *m_head;
-	if((mtod(m, intptr_t) & 3) != 0) {
+	if (! arge_mbuf_chain_is_tx_aligned(m)) {
 		m = m_defrag(*m_head, M_DONTWAIT);
 		if (m == NULL) {
 			*m_head = NULL;