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

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Date:	Tue, 14 Oct 2014 20:55:55 +0000
From:	Paul Zimmerman <Paul.Zimmerman@...opsys.com>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.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

> 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?

-- 
Paul

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