linux-kernel - RE: drivers/usb/chipidea/core.c:657 ci_usb_role_switch_set() error: double unlocked 'ci->lock' (orig line 638)

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Date:   Sat, 8 Aug 2020 02:44:31 +0000
From:   Jun Li <jun.li@....com>
To:     kernel test robot <lkp@...el.com>
CC:     "kbuild-all@...ts.01.org" <kbuild-all@...ts.01.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Peter Chen <peter.chen@....com>
Subject: RE: drivers/usb/chipidea/core.c:657 ci_usb_role_switch_set() error:
 double unlocked 'ci->lock' (orig line 638)

Hi,

> -----Original Message-----
> From: kernel test robot <lkp@...el.com>
> Sent: Friday, August 7, 2020 6:00 PM
> To: Jun Li <jun.li@....com>
> Cc: kbuild-all@...ts.01.org; linux-kernel@...r.kernel.org; Peter Chen
> <peter.chen@....com>
> Subject: drivers/usb/chipidea/core.c:657 ci_usb_role_switch_set() error: double
> unlocked 'ci->lock' (orig line 638)
> 
> tree:
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.o
> rg%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git&amp;data=02%7C01%
> 7Cjun.li%40nxp.com%7Ce261827f14f6446b3e8308d83ab8c407%7C686ea1d3bc2b4c6fa92cd9
> 9c5c301635%7C0%7C0%7C637323912694699319&amp;sdata=ioDexF9tIACz%2BlnZC%2BzZsiFz
> iOeeLembxqr9PwE%2Fpgg%3D&amp;reserved=0 master
> head:   86cfccb66937dd6cbf26ed619958b9e587e6a115
> commit: 05559f10ed797b79f7fa47313682c48919a2b111 usb: chipidea: add role switch
> class support
> date:   12 months ago
> config: parisc-randconfig-m031-20200807 (attached as .config)
> compiler: hppa-linux-gcc (GCC) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
> 
> smatch warnings:
> drivers/usb/chipidea/core.c:657 ci_usb_role_switch_set() error: double unlocked
> 'ci->lock' (orig line 638)
> 
> vim +657 drivers/usb/chipidea/core.c
> 
>    615
>    616	static int ci_usb_role_switch_set(struct device *dev, enum usb_role role)
>    617	{
>    618		struct ci_hdrc *ci = dev_get_drvdata(dev);
>    619		struct ci_hdrc_cable *cable = NULL;
>    620		enum usb_role current_role = ci_role_to_usb_role(ci);
>    621		unsigned long flags;
>    622
>    623		if (current_role == role)
>    624			return 0;
>    625
>    626		pm_runtime_get_sync(ci->dev);
>    627		/* Stop current role */
>    628		spin_lock_irqsave(&ci->lock, flags);
>    629		if (current_role == USB_ROLE_DEVICE)
>    630			cable = &ci->platdata->vbus_extcon;
>    631		else if (current_role == USB_ROLE_HOST)
>    632			cable = &ci->platdata->id_extcon;
>    633
>    634		if (cable) {
>    635			cable->changed = true;
>    636			cable->connected = false;
>    637			ci_irq(ci->irq, ci);
>  > 638			spin_unlock_irqrestore(&ci->lock, flags);
>    639			if (ci->wq && role != USB_ROLE_NONE)
>    640				flush_workqueue(ci->wq);
>    641			spin_lock_irqsave(&ci->lock, flags);

Here we hold the lock again.

>    642		}
>    643
>    644		cable = NULL;
>    645
>    646		/* Start target role */
>    647		if (role == USB_ROLE_DEVICE)
>    648			cable = &ci->platdata->vbus_extcon;
>    649		else if (role == USB_ROLE_HOST)
>    650			cable = &ci->platdata->id_extcon;
>    651
>    652		if (cable) {
>    653			cable->changed = true;
>    654			cable->connected = true;
>    655			ci_irq(ci->irq, ci);
>    656		}
>  > 657		spin_unlock_irqrestore(&ci->lock, flags);

So it's fine to unlock here.

Thanks
Li Jun
>    658		pm_runtime_put_sync(ci->dev);
>    659
>    660		return 0;
>    661	}
>    662
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
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