Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758742AbcCVM4e (ORCPT ); Tue, 22 Mar 2016 08:56:34 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:42383 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752032AbcCVM41 (ORCPT ); Tue, 22 Mar 2016 08:56:27 -0400 Subject: Re: [PATCH] spi: rockchip: fix warning of static check To: Shawn Lin , Mark Brown References: <1458646574-12830-1-git-send-email-shawn.lin@rock-chips.com> CC: , , Doug Anderson , Dan Carpenter From: Vladimir Zapolskiy Message-ID: <56F140E4.8010906@mentor.com> Date: Tue, 22 Mar 2016 14:56:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Icedove/38.1.0 MIME-Version: 1.0 In-Reply-To: <1458646574-12830-1-git-send-email-shawn.lin@rock-chips.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [137.202.0.76] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2165 Lines: 67 Hi Shawn, On 22.03.2016 13:36, Shawn Lin wrote: > Let's improve the check with -EPROBE_DEFER, otherwise > we may pass on null pointer to PTR_ERR. That causes the > static checker warning: passing zero to 'PTR_ERR'. > > Reported-by: Dan Carpenter > Cc: Doug Anderson > Cc: Dan Carpenter > Signed-off-by: Shawn Lin > --- > > drivers/spi/spi-rockchip.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c > index bfeb0d4..2cb36d9 100644 > --- a/drivers/spi/spi-rockchip.c > +++ b/drivers/spi/spi-rockchip.c > @@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev) > rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx"); > if (IS_ERR_OR_NULL(rs->dma_tx.ch)) { > /* Check tx to see if we need defer probing driver */ > - if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) { > + if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) { won't it be easier to change dma_request_slave_channel() to dma_request_chan() or dma_request_slave_channel_reason() and replace strange IS_ERR_OR_NULL() check with IS_ERR() one? AFAIU that's almost what has been suggested by Doug and it is a better fix than this one published. At the moment check for IS_ERR_OR_NULL() is too aggressive and quite confusing, because dma_request_slave_channel() never returns NULL. > ret = -EPROBE_DEFER; > goto err_get_fifo_len; > } > dev_warn(rs->dev, "Failed to request TX DMA channel\n"); > + rs->dma_tx.ch = NULL; > } > > rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx"); > - if (!rs->dma_rx.ch) { > - if (rs->dma_tx.ch) { > + if (IS_ERR_OR_NULL(rs->dma_rx.ch)) { > + if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) { Same as above. > dma_release_channel(rs->dma_tx.ch); > rs->dma_tx.ch = NULL; > + ret = -EPROBE_DEFER; > + goto err_get_fifo_len; > } > dev_warn(rs->dev, "Failed to request RX DMA channel\n"); > + rs->dma_rx.ch = NULL; > } > > if (rs->dma_tx.ch && rs->dma_rx.ch) { > -- With best wishes, Vladimir