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

[Jun Li]

Hi,

> -----Original Message-----
> From: kernel test robot <l...@intel.com>
> Sent: Friday, August 7, 2020 6:00 PM
> To: Jun Li <jun...@nxp.com>
> Cc: kbuild-...@lists.01.org; linux-kernel@vger.kernel.org; Peter Chen
> <peter.c...@nxp.com>
> Subject: drivers/usb/chipidea/core.c:657 ci_usb_role_switch_set() error: 
> double
> unlocked 'ci->lock' (orig line 638)
> 
> tree:
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> 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 <l...@intel.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
> 
> ---
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