Re: [PATCH 21/23] scsi_dh_alua: update all port states

[Hannes Reinecke <hare@suse.de>]

On 09/22/2015 10:04 PM, Ewan Milne wrote:
> On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote:
>> When we read in the target port group state we should be
>> updating all affected port groups, otherwise we risk
>> running out of sync.
>>
>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>> ---
>>  drivers/scsi/device_handler/scsi_dh_alua.c | 21 +++++++++++++++++----
>>  1 file changed, 17 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
>> index 8717fd3..2fa985e 100644
>> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
>> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
>> @@ -477,11 +477,13 @@ static int alua_check_sense(struct scsi_device *sdev,
>>  static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
>>  {
>>  	struct scsi_sense_hdr sense_hdr;
>> +	struct alua_port_group *tmp_pg;
>>  	int len, k, off, valid_states = 0, bufflen = ALUA_RTPG_SIZE;
>>  	unsigned char *ucp, *buff;
>>  	unsigned err, retval;
>>  	unsigned int tpg_desc_tbl_off;
>>  	unsigned char orig_transition_tmo;
>> +	unsigned long flags;
>>  
>>  	if (!pg->expiry) {
>>  		if (!pg->transition_tmo)
>> @@ -584,17 +586,28 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
>>  	else
>>  		tpg_desc_tbl_off = 4;
>>  
>> +	spin_lock_irqsave(&port_group_lock, flags);
>>  	for (k = tpg_desc_tbl_off, ucp = buff + tpg_desc_tbl_off;
>>  	     k < len;
>>  	     k += off, ucp += off) {
> 
> "ucp" is not really a good variable name, it matches nothing in the T10
> spec.  The structure is a "Target Port Group Descriptor".  I realize it
> was already there, but maybe this is a good opportunity to change it?
> 
Doug Gilbert is to blame; I've copied this section over from sg3_utils :-)
But yeah, I can set it to eg 'desc'.

>>  
>> -		if (pg->group_id == get_unaligned_be16(&ucp[2])) {
>> -			pg->state = ucp[0] & 0x0f;
>> -			pg->pref = ucp[0] >> 7;
>> -			valid_states = ucp[1];
>> +		list_for_each_entry(tmp_pg, &port_group_list, node) {
>> +			u16 group_id = get_unaligned_be16(&ucp[2]);
> 
> This is invariant and should be outside the loop.
> 
True.

Cheers,

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