svn commit: r290339 - head/sys/dev/ath

[Adrian Chadd]

Author: adrian
Date: Tue Nov  3 21:11:30 2015
New Revision: 290339
URL: https://svnweb.freebsd.org/changeset/base/290339

Log:
  ath(4) - don't try to free buffers / return an error if we've committed
  to transmit the buffer.
  
  ath_tx_start() may manipulate/reallocate the mbuf as part of the DMA
  code, so we can't expect the mbuf can be returned back to the caller.
  Now, the net80211 ifnet work changed the semantics slightly so
  if an error is returned here, the mbuf/reference is freed by the
  caller (here, it's net80211.)
  
  So, once we reach ath_tx_start(), we never return failure.  If we fail
  then we still return OK and we free the mbuf/noderef ourselves, and
  we increment OERRORS.

Modified:
  head/sys/dev/ath/if_ath.c

Modified: head/sys/dev/ath/if_ath.c
==============================================================================
--- head/sys/dev/ath/if_ath.c	Tue Nov  3 21:03:26 2015	(r290338)
+++ head/sys/dev/ath/if_ath.c	Tue Nov  3 21:11:30 2015	(r290339)
@@ -3320,6 +3320,9 @@ nextfrag:
 	 *
 	 * Note: if this fails, then the mbufs are freed but
 	 * not the node reference.
+	 *
+	 * So, we now have to free the node reference ourselves here
+	 * and return OK up to the stack.
 	 */
 	next = m->m_nextpkt;
 	if (ath_tx_start(sc, ni, bf, m)) {
@@ -3336,7 +3339,14 @@ reclaim:
 		 */
 		ath_txfrag_cleanup(sc, &frags, ni);
 		ATH_TXBUF_UNLOCK(sc);
-		retval = ENOBUFS;
+
+		/*
+		 * XXX: And free the node/return OK; ath_tx_start() may have
+		 *      modified the buffer.  We currently have no way to
+		 *      signify that the mbuf was freed but there was an error.
+		 */
+		ieee80211_free_node(ni);
+		retval = 0;
 		goto finish;
 	}