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

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Date:	Sat, 12 Dec 2015 03:06:30 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"ohering@...e.com" <ohering@...e.com>,
	"jbottomley@...allels.com" <jbottomley@...allels.com>,
	"hch@...radead.org" <hch@...radead.org>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"apw@...onical.com" <apw@...onical.com>,
	"vkuznets@...hat.com" <vkuznets@...hat.com>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	"martin.petersen@...cle.com" <martin.petersen@...cle.com>
Subject: RE: [PATCH 3/4] scsi: storvsc: Refactor the code in
 storvsc_channel_init()



> -----Original Message-----
> From: Dan Carpenter [mailto:dan.carpenter@...cle.com]
> Sent: Friday, December 11, 2015 2:41 AM
> To: KY 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.

Thanks Dan; I will cleanup the code and resend.

Regards,

K. Y



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