linux-kernel - Re: [PATCH] usb: dwc2: gadget: sparse warning of context imbalance

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Date:	Wed, 15 Oct 2014 14:47:57 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Paul Zimmerman <Paul.Zimmerman@...opsys.com>
Cc:	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"balbi@...com" <balbi@...com>
Subject: Re: [PATCH] usb: dwc2: gadget: sparse warning of context imbalance

On Tue, Oct 14, 2014 at 08:55:55PM +0000, Paul Zimmerman wrote:
> > From: Sudip Mukherjee [mailto:sudipm.mukherjee@...il.com]
> > Sent: Friday, October 10, 2014 6:10 AM
> > 
> > sparse was giving the following warning:
> > 	warning: context imbalance in 's3c_hsotg_ep_enable'
> > 	- different lock contexts for basic block
> > 
> > we were returning ENOMEM while still holding the spinlock.
> > The sparse warning was fixed by releasing the spinlock before return.
> > 
> > Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
> > ---
> >  drivers/usb/dwc2/gadget.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> > index 7b5856f..046e90d 100644
> > --- a/drivers/usb/dwc2/gadget.c
> > +++ b/drivers/usb/dwc2/gadget.c
> > @@ -2561,8 +2561,10 @@ static int s3c_hsotg_ep_enable(struct usb_ep *ep,
> >  			hs_ep->fifo_size = val;
> >  			break;
> >  		}
> > -		if (i == 8)
> > +		if (i == 8) {
> > +			spin_unlock_irqrestore(&hsotg->lock, flags);
> >  			return -ENOMEM;
> > +		}
> >  	}
> > 
> >  	/* for non control endpoints, set PID to D0 */
> 
> For a long function like this, I'd rather keep a single return point at
> the end. Something like this:
> 
>  		}
> -		if (i == 8)
> -			return -ENOMEM;
> +		if (i == 8) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
>  	}
> ...
>  
> +out:
>  	spin_unlock_irqrestore(&hsotg->lock, flags);
>  	return ret;
>  }
> 
> Care to respin the patch like that?
> 
sure , modified patch will be in your inbox in a short time. 

thanks
sudip
> -- 
> Paul
> 
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