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Date:      Fri, 23 Sep 2016 08:26:45 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject:   svn commit: r306243 - stable/11/sys/dev/mlx5/mlx5_en
Message-ID:  <201609230826.u8N8QjSR051792@repo.freebsd.org>
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Author: hselasky
Date: Fri Sep 23 08:26:45 2016
New Revision: 306243
URL: https://svnweb.freebsd.org/changeset/base/306243

Log:
  MFC r305877:
  mlx5en: Fix duplicate mbuf free-by-code.
  
  When mlx5e_sq_xmit() returns an error code and the mbuf pointer is set,
  we should not free the mbuf, because the caller will keep the mbuf in
  the drbr. Make sure the mbuf pointer is correctly set upon function
  exit.
  
  Sponsored by:	Mellanox Technologies

Modified:
  stable/11/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c
==============================================================================
--- stable/11/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c	Fri Sep 23 08:26:02 2016	(r306242)
+++ stable/11/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c	Fri Sep 23 08:26:45 2016	(r306243)
@@ -224,10 +224,8 @@ mlx5e_sq_xmit(struct mlx5e_sq *sq, struc
 		/* Send one multi NOP message instead of many */
 		mlx5e_send_nop(sq, (pi + 1) * MLX5_SEND_WQEBB_NUM_DS);
 		pi = ((~sq->pc) & sq->wq.sz_m1);
-		if (pi < (MLX5_SEND_WQE_MAX_WQEBBS - 1)) {
-			m_freem(mb);
+		if (pi < (MLX5_SEND_WQE_MAX_WQEBBS - 1))
 			return (ENOMEM);
-		}
 	}
 
 	/* Setup local variables */
@@ -338,10 +336,8 @@ mlx5e_sq_xmit(struct mlx5e_sq *sq, struc
 		    mb, segs, &nsegs, BUS_DMA_NOWAIT);
 	}
 	/* Catch errors */
-	if (err != 0) {
+	if (err != 0)
 		goto tx_drop;
-	}
-	*mbp = mb;
 
 	for (x = 0; x != nsegs; x++) {
 		if (segs[x].ds_len == 0)
@@ -374,6 +370,7 @@ skip_dma:
 		bus_dmamap_sync(sq->dma_tag, sq->mbuf[pi].dma_map, BUS_DMASYNC_PREWRITE);
 
 	sq->stats.packets++;
+	*mbp = NULL;	/* safety clear */
 	return (0);
 
 tx_drop:

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