From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH 8/8] serial: tegra: Correct error handling on DMA setup Date: Wed, 20 May 2015 10:51:59 +0100 Message-ID: <555C593F.5040107@nvidia.com> References: <1430835479-6613-1-git-send-email-jonathanh@nvidia.com> <1430835479-6613-9-git-send-email-jonathanh@nvidia.com> <5551CD25.4030206@nvidia.com> <555309F4.1080306@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alexandre Courbot Cc: Laxman Dewangan , Greg Kroah-Hartman , Jiri Slaby , linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Linux Kernel Mailing List List-Id: linux-tegra@vger.kernel.org On 20/05/15 04:57, Alexandre Courbot wrote: [snip] > There may still be a leak (that is not related to your patch) in the > RX path though: > > dma_buf = dma_alloc_coherent(...); > ret = dmaengine_slave_config(...); > if (ret < 0) { > ... > goto scrub; > } > > tup->rx_dma_buf_virt = dma_buf; > tup->rx_dma_buf_phys = dma_phys; > > scrub: > dma_release_channel(dma_chan); > return ret; > > It seems that if dmaengine_slave_config() fails, then the result of > dma_alloc_coherent() remains purely local to the function and is never > freed. Or am I missing something again? Yes, you are right here. Actually, this would be applicable to both RX and TX paths because in the TX path the buffer would not be unmapped. I will generated a separate patch for fix this. How does the following look? diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c index 3b63f103f0c9..cf0133ae762d 100644 --- a/drivers/tty/serial/serial-tegra.c +++ b/drivers/tty/serial/serial-tegra.c @@ -999,6 +999,12 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup, dma_release_channel(dma_chan); return -ENOMEM; } + dma_sconfig.src_addr = tup->uport.mapbase; + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.src_maxburst = 4; + tup->rx_dma_chan = dma_chan; + tup->rx_dma_buf_virt = dma_buf; + tup->rx_dma_buf_phys = dma_phys; } else { dma_phys = dma_map_single(tup->uport.dev, tup->uport.state->xmit.buf, UART_XMIT_SIZE, @@ -1009,39 +1015,23 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup, return -ENOMEM; } dma_buf = tup->uport.state->xmit.buf; - } - - if (dma_to_memory) { - dma_sconfig.src_addr = tup->uport.mapbase; - dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; - dma_sconfig.src_maxburst = 4; - } else { dma_sconfig.dst_addr = tup->uport.mapbase; dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; dma_sconfig.dst_maxburst = 16; + tup->tx_dma_chan = dma_chan; + tup->tx_dma_buf_virt = dma_buf; + tup->tx_dma_buf_phys = dma_phys; } ret = dmaengine_slave_config(dma_chan, &dma_sconfig); if (ret < 0) { dev_err(tup->uport.dev, "Dma slave config failed, err = %d\n", ret); - goto scrub; + tegra_uart_dma_channel_free(tup, dma_to_memory); + return ret; } - if (dma_to_memory) { - tup->rx_dma_chan = dma_chan; - tup->rx_dma_buf_virt = dma_buf; - tup->rx_dma_buf_phys = dma_phys; - } else { - tup->tx_dma_chan = dma_chan; - tup->tx_dma_buf_virt = dma_buf; - tup->tx_dma_buf_phys = dma_phys; - } return 0; - -scrub: - tegra_uart_dma_channel_free(tup, dma_to_memory); - return ret; } Cheers Jon From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752979AbbETJwL (ORCPT ); Wed, 20 May 2015 05:52:11 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:15405 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751502AbbETJwH (ORCPT ); Wed, 20 May 2015 05:52:07 -0400 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Wed, 20 May 2015 02:49:15 -0700 Message-ID: <555C593F.5040107@nvidia.com> Date: Wed, 20 May 2015 10:51:59 +0100 From: Jon Hunter User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Alexandre Courbot CC: Laxman Dewangan , Greg Kroah-Hartman , Jiri Slaby , , "linux-tegra@vger.kernel.org" , Linux Kernel Mailing List Subject: Re: [PATCH 8/8] serial: tegra: Correct error handling on DMA setup References: <1430835479-6613-1-git-send-email-jonathanh@nvidia.com> <1430835479-6613-9-git-send-email-jonathanh@nvidia.com> <5551CD25.4030206@nvidia.com> <555309F4.1080306@nvidia.com> In-Reply-To: X-Originating-IP: [10.21.134.107] X-ClientProxiedBy: UKMAIL102.nvidia.com (10.26.138.15) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/05/15 04:57, Alexandre Courbot wrote: [snip] > There may still be a leak (that is not related to your patch) in the > RX path though: > > dma_buf = dma_alloc_coherent(...); > ret = dmaengine_slave_config(...); > if (ret < 0) { > ... > goto scrub; > } > > tup->rx_dma_buf_virt = dma_buf; > tup->rx_dma_buf_phys = dma_phys; > > scrub: > dma_release_channel(dma_chan); > return ret; > > It seems that if dmaengine_slave_config() fails, then the result of > dma_alloc_coherent() remains purely local to the function and is never > freed. Or am I missing something again? Yes, you are right here. Actually, this would be applicable to both RX and TX paths because in the TX path the buffer would not be unmapped. I will generated a separate patch for fix this. How does the following look? diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c index 3b63f103f0c9..cf0133ae762d 100644 --- a/drivers/tty/serial/serial-tegra.c +++ b/drivers/tty/serial/serial-tegra.c @@ -999,6 +999,12 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup, dma_release_channel(dma_chan); return -ENOMEM; } + dma_sconfig.src_addr = tup->uport.mapbase; + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.src_maxburst = 4; + tup->rx_dma_chan = dma_chan; + tup->rx_dma_buf_virt = dma_buf; + tup->rx_dma_buf_phys = dma_phys; } else { dma_phys = dma_map_single(tup->uport.dev, tup->uport.state->xmit.buf, UART_XMIT_SIZE, @@ -1009,39 +1015,23 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup, return -ENOMEM; } dma_buf = tup->uport.state->xmit.buf; - } - - if (dma_to_memory) { - dma_sconfig.src_addr = tup->uport.mapbase; - dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; - dma_sconfig.src_maxburst = 4; - } else { dma_sconfig.dst_addr = tup->uport.mapbase; dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; dma_sconfig.dst_maxburst = 16; + tup->tx_dma_chan = dma_chan; + tup->tx_dma_buf_virt = dma_buf; + tup->tx_dma_buf_phys = dma_phys; } ret = dmaengine_slave_config(dma_chan, &dma_sconfig); if (ret < 0) { dev_err(tup->uport.dev, "Dma slave config failed, err = %d\n", ret); - goto scrub; + tegra_uart_dma_channel_free(tup, dma_to_memory); + return ret; } - if (dma_to_memory) { - tup->rx_dma_chan = dma_chan; - tup->rx_dma_buf_virt = dma_buf; - tup->rx_dma_buf_phys = dma_phys; - } else { - tup->tx_dma_chan = dma_chan; - tup->tx_dma_buf_virt = dma_buf; - tup->tx_dma_buf_phys = dma_phys; - } return 0; - -scrub: - tegra_uart_dma_channel_free(tup, dma_to_memory); - return ret; } Cheers Jon