From mboxrd@z Thu Jan 1 00:00:00 1970 From: Troy Kisky Subject: Re: [PATCH net 1/1] net: fec: update dirty_tx even if no skb Date: Sat, 7 May 2016 11:56:50 -0700 Message-ID: <0288eea6-9669-d763-4bd8-9438ce0c1f94@boundarydevices.com> References: <1461290434-18462-1-git-send-email-troy.kisky@boundarydevices.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Fabio Estevam , "l.stach@pengutronix.de" , "andrew@lunn.ch" , "tremyfr@gmail.com" , "gerg@uclinux.org" , "linux-arm-kernel@lists.infradead.org" , "johannes@sipsolutions.net" , "stillcompiling@gmail.com" , "sergei.shtylyov@cogentembedded.com" , "arnd@arndb.de" , "holgerschurig@gmail.com" To: Fugang Duan , "netdev@vger.kernel.org" , "davem@davemloft.net" , "lznuaa@gmail.com" Return-path: Received: from mail-pf0-f173.google.com ([209.85.192.173]:35976 "EHLO mail-pf0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750990AbcEGS4v (ORCPT ); Sat, 7 May 2016 14:56:51 -0400 Received: by mail-pf0-f173.google.com with SMTP id c189so62981214pfb.3 for ; Sat, 07 May 2016 11:56:51 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 4/21/2016 10:59 PM, Fugang Duan wrote: > From: Troy Kisky Sent: Friday, April 22, 2016 10:01 AM >> To: netdev@vger.kernel.org; davem@davemloft.net; Fugang Duan >> ; lznuaa@gmail.com >> Cc: Fabio Estevam ; l.stach@pengutronix.de; >> andrew@lunn.ch; tremyfr@gmail.com; gerg@uclinux.org; linux-arm- >> kernel@lists.infradead.org; johannes@sipsolutions.net; >> stillcompiling@gmail.com; sergei.shtylyov@cogentembedded.com; >> arnd@arndb.de; holgerschurig@gmail.com; Troy Kisky >> >> Subject: [PATCH net 1/1] net: fec: update dirty_tx even if no skb >> >> If dirty_tx isn't updated, then dma_unmap_single will be called twice. >> >> This fixes a >> [ 58.420980] ------------[ cut here ]------------ >> [ 58.425667] WARNING: CPU: 0 PID: 377 at /home/schurig/d/mkarm/linux- >> 4.5/lib/dma-debug.c:1096 check_unmap+0x9d0/0xab8() >> [ 58.436405] fec 2188000.ethernet: DMA-API: device driver tries to free DMA >> memory it has not allocated [device address=0x0000000000000000] [size=66 >> bytes] >> >> encountered by Holger >> >> Signed-off-by: Troy Kisky >> Tested-by: >> --- >> drivers/net/ethernet/freescale/fec_main.c | 8 +++----- >> 1 file changed, 3 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/net/ethernet/freescale/fec_main.c >> b/drivers/net/ethernet/freescale/fec_main.c >> index 08243c2..b71654c 100644 >> --- a/drivers/net/ethernet/freescale/fec_main.c >> +++ b/drivers/net/ethernet/freescale/fec_main.c >> @@ -1197,10 +1197,8 @@ fec_enet_tx_queue(struct net_device *ndev, u16 >> queue_id) >> fec16_to_cpu(bdp->cbd_datlen), >> DMA_TO_DEVICE); >> bdp->cbd_bufaddr = cpu_to_fec32(0); >> - if (!skb) { >> - bdp = fec_enet_get_nextdesc(bdp, &txq->bd); >> - continue; >> - } >> + if (!skb) >> + goto skb_done; >> >> /* Check for errors. */ >> if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC | @@ -1239,7 >> +1237,7 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id) >> >> /* Free the sk buffer associated with this last transmit */ >> dev_kfree_skb_any(skb); >> - >> +skb_done: >> /* Make sure the update to bdp and tx_skbuff are performed >> * before dirty_tx >> */ >> -- >> 2.5.0 > > The patch is fine for me. > Can you review below patch that also fix the issue. It can take much effort due to less rmb() and READ_ONCE() operation that is very sensitive for duplex Gbps test for i.MX6SX/i.MX7d SOC. (i.MX6SX can reach at 1.4Gbps, i.MX7D can reach at 1.8Gbps.) > Am I supposed to do anything else to get this patch into net ?