Re: [PATCH] Restart scsi_device_lookup_by_target

[Hannes Reinecke <hare@suse.de>]

Hi Matthew,

Matthew Wilcox wrote:
> On Tue, Jan 13, 2009 at 02:50:30PM +0100, Hannes Reinecke wrote:
>> @@ -1131,14 +1137,15 @@ EXPORT_SYMBOL(__scsi_device_lookup_by_target);
>>  struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
>>  						 uint lun)
>>  {
>> -	struct scsi_device *sdev;
>> +	struct scsi_device *sdev = NULL;
>>  	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
>>  	unsigned long flags;
>>  
>>  	spin_lock_irqsave(shost->host_lock, flags);
>> -	sdev = __scsi_device_lookup_by_target(starget, lun);
>> + restart:
>> +	sdev = __scsi_device_lookup_by_target(starget, sdev, lun);
>>  	if (sdev && scsi_device_get(sdev))
>> -		sdev = NULL;
>> +		goto restart;
>>  	spin_unlock_irqrestore(shost->host_lock, flags);
>>  
>>  	return sdev;
> 
> Backwards jumps are generally disapproved of.  How about:
> 
> 	spin_lock_irqsave(shost->host_lock, flags);
> 	for (;;) {
> 		sdev = __scsi_device_lookup_by_target(starget, sdev, lun);
> 		if (!sdev || !scsi_device_get(sdev))
> 			break;
> 	}
> 	spin_unlock_irqrestore(shost->host_lock, flags);
> 
> 
I must say I don't really like the for(;;) construct.
And it's really confusing as we want to find an sdev, so breaking
if it's _not_ found is ... weird.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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