From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA39AECE588 for ; Tue, 15 Oct 2019 11:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B42621835 for ; Tue, 15 Oct 2019 11:16:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726437AbfJOLQb (ORCPT ); Tue, 15 Oct 2019 07:16:31 -0400 Received: from foss.arm.com ([217.140.110.172]:36032 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbfJOLQa (ORCPT ); Tue, 15 Oct 2019 07:16:30 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0E40F337; Tue, 15 Oct 2019 04:16:30 -0700 (PDT) Received: from e121166-lin.cambridge.arm.com (unknown [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 262F63F68E; Tue, 15 Oct 2019 04:16:29 -0700 (PDT) Date: Tue, 15 Oct 2019 12:16:24 +0100 From: Lorenzo Pieralisi To: Remi Pommarel Cc: Thomas Petazzoni , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] PCI: aardvark: Don't rely on jiffies while holding spinlock Message-ID: <20191015111623.GA7193@e121166-lin.cambridge.arm.com> References: <20190927085502.1758-1-repk@triplefau.lt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190927085502.1758-1-repk@triplefau.lt> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 27, 2019 at 10:55:02AM +0200, Remi Pommarel wrote: > advk_pcie_wait_pio() can be called while holding a spinlock (from > pci_bus_read_config_dword()), then depends on jiffies in order to > timeout while polling on PIO state registers. In the case the PIO > transaction failed, the timeout will never happen and will also cause > the cpu to stall. > > This decrements a variable and wait instead of using jiffies. > > Signed-off-by: Remi Pommarel > --- > Changes since v1: > - Reduce polling delay > - Change size_t into int for loop counter > Changes since v2: > - Keep timeout to 1ms by increasing retry counter > --- > drivers/pci/controller/pci-aardvark.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) Applied to pci/aardvark, thanks. Lorenzo > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index fc0fe4d4de49..7b5c9d6c8706 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -175,7 +175,8 @@ > (PCIE_CONF_BUS(bus) | PCIE_CONF_DEV(PCI_SLOT(devfn)) | \ > PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where)) > > -#define PIO_TIMEOUT_MS 1 > +#define PIO_RETRY_CNT 500 > +#define PIO_RETRY_DELAY 2 /* 2 us*/ > > #define LINK_WAIT_MAX_RETRIES 10 > #define LINK_WAIT_USLEEP_MIN 90000 > @@ -383,17 +384,16 @@ static void advk_pcie_check_pio_status(struct advk_pcie *pcie) > static int advk_pcie_wait_pio(struct advk_pcie *pcie) > { > struct device *dev = &pcie->pdev->dev; > - unsigned long timeout; > + int i; > > - timeout = jiffies + msecs_to_jiffies(PIO_TIMEOUT_MS); > - > - while (time_before(jiffies, timeout)) { > + for (i = 0; i < PIO_RETRY_CNT; i++) { > u32 start, isr; > > start = advk_readl(pcie, PIO_START); > isr = advk_readl(pcie, PIO_ISR); > if (!start && isr) > return 0; > + udelay(PIO_RETRY_DELAY); > } > > dev_err(dev, "config read/write timed out\n"); > -- > 2.20.1 >