Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935217AbbKTWoN (ORCPT ); Fri, 20 Nov 2015 17:44:13 -0500 Received: from smtprelay2.synopsys.com ([198.182.60.111]:42034 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759452AbbKTWoL convert rfc822-to-8bit (ORCPT ); Fri, 20 Nov 2015 17:44:11 -0500 From: John Youn To: Douglas Anderson , John Youn , "balbi@ti.com" CC: Yunzhi Li , =?iso-8859-1?Q?Heiko_St=FCbner?= , "linux-rockchip@lists.infradead.org" , Julius Werner , "gregory.herrero@intel.com" , "yousaf.kaukab@intel.com" , "dinguyen@opensource.altera.com" , "gregkh@linuxfoundation.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v5 1/2] usb: dwc2: host: Add missing spinlock in dwc2_hcd_reset_func() Thread-Topic: [PATCH v5 1/2] usb: dwc2: host: Add missing spinlock in dwc2_hcd_reset_func() Thread-Index: AQHRI7XS5Lfp+NL0sEWMKh8kMNeYmg== Date: Fri, 20 Nov 2015 22:44:08 +0000 Message-ID: <2B3535C5ECE8B5419E3ECBE30077290901DC3DAFB7@US01WEMBX2.internal.synopsys.com> References: <1448039188-14296-1-git-send-email-dianders@chromium.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.10.161.90] Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1914 Lines: 58 On 11/20/2015 9:06 AM, Douglas Anderson wrote: > The dwc2_hcd_reset_func() function is only ever called directly by a > delayed work function. As such no locks are already held when the > function is called. > > Doing a read-modify-write of CPU registers and setting fields in the > main hsotg data structure is a bad idea without locks. Let's add > locks. > > The bug was found by code inspection only. It turns out that the > dwc2_hcd_reset_func() is only ever called today if the > "host_support_fs_ls_low_power" parameter is enabled and no code in > mainline enables that parameter. Thus no known issues in mainline are > fixed by this patch, but it's still probably wise to fix the function. > > Signed-off-by: Douglas Anderson > --- > Changes in v5: > - New for v5 of the series > > drivers/usb/dwc2/hcd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c > index 42b6c5127618..e8924cecc83a 100644 > --- a/drivers/usb/dwc2/hcd.c > +++ b/drivers/usb/dwc2/hcd.c > @@ -2357,13 +2357,19 @@ static void dwc2_hcd_reset_func(struct work_struct *work) > { > struct dwc2_hsotg *hsotg = container_of(work, struct dwc2_hsotg, > reset_work.work); > + unsigned long flags; > u32 hprt0; > > dev_dbg(hsotg->dev, "USB RESET function called\n"); > + > + spin_lock_irqsave(&hsotg->lock, flags); > + > hprt0 = dwc2_read_hprt0(hsotg); > hprt0 &= ~HPRT0_RST; > dwc2_writel(hprt0, hsotg->regs + HPRT0); > hsotg->flags.b.port_reset_change = 1; > + > + spin_unlock_irqrestore(&hsotg->lock, flags); > } > > /* > Acked-by: John Youn John -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/