linux-kernel - Re: [PATCH 3/4] scsi: storvsc: Refactor the code in storvsc_channel

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Date:	Fri, 11 Dec 2015 13:40:47 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	"K. Y. Srinivasan" <kys@...rosoft.com>
Cc:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, ohering@...e.com,
	jbottomley@...allels.com, hch@...radead.org,
	linux-scsi@...r.kernel.org, apw@...onical.com, vkuznets@...hat.com,
	jasowang@...hat.com, martin.petersen@...cle.com
Subject: Re: [PATCH 3/4] scsi: storvsc: Refactor the code in
 storvsc_channel_init()

On Thu, Dec 10, 2015 at 04:14:19PM -0800, K. Y. Srinivasan wrote:
> @@ -753,27 +740,62 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
>  			       VM_PKT_DATA_INBAND,
>  			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>  	if (ret != 0)
> -		goto cleanup;
> +		goto done;
>  
>  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
>  	if (t == 0) {
>  		ret = -ETIMEDOUT;
> -		goto cleanup;
> +		goto done;
>  	}
>  
> +	if (!status_check)
> +		goto done;

See?  This goto looks exactly the same as the earlier buggy goto but
it's actually correct.  Meanwhile if you just used an explicit
"return 0;" then it would be easy to understand.

I rant about this all the time but it's because it's bad deliberately.
It's normal to have bugs, but this deliberate stuff really I can't
understand it...

> +
>  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
>  	    vstor_packet->status != 0) {
>  		ret = -EINVAL;
> -		goto cleanup;
> +		goto done;
>  	}
>  
> +done:
> +	return ret;
> +}
> +
> +static int storvsc_channel_init(struct hv_device *device, bool is_fc)
> +{
> +	struct storvsc_device *stor_device;
> +	struct storvsc_cmd_request *request;
> +	struct vstor_packet *vstor_packet;
> +	int ret, i;
> +	int max_chns;
> +	bool process_sub_channels = false;
> +
> +	stor_device = get_out_stor_device(device);
> +	if (!stor_device)
> +		return -ENODEV;
> +
> +	request = &stor_device->init_request;
> +	vstor_packet = &request->vstor_packet;
> +
> +	/*
> +	 * Now, initiate the vsc/vsp initialization protocol on the open
> +	 * channel
> +	 */
> +	memset(request, 0, sizeof(struct storvsc_cmd_request));
> +	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
> +	ret = storvsc_execute_vstor_op(device, request, true);
> +	if (ret)
> +		goto cleanup;

10 lines earlier there is an explicit "return -ENODEV" so it's not as if
writing explicit returns will kill you.

regards,
dan carpenter

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