[dm-devel] Re: [PATCH] Remove capping from dev_loss_tmo

[Mike Christie]

Hannes Reinecke wrote:
> Mike Christie wrote:
>> Hannes Reinecke wrote:
>>> diff --git a/drivers/scsi/scsi_transport_fc.c
>>> b/drivers/scsi/scsi_transport_fc.c
>>> index 573ce21..6f39bf4 100644
>>> --- a/drivers/scsi/scsi_transport_fc.c
>>> +++ b/drivers/scsi/scsi_transport_fc.c
>>> @@ -475,7 +475,8 @@ MODULE_PARM_DESC(dev_loss_tmo,
>>>           "Maximum number of seconds that the FC transport should"
>>>           " insulate the loss of a remote port. Once this value is"
>>>           " exceeded, the scsi target is removed. Value should be"
>>> -         " between 1 and SCSI_DEVICE_BLOCK_MAX_TIMEOUT.");
>>> +         " between 1 and SCSI_DEVICE_BLOCK_MAX_TIMEOUT if"
>>> +         " fast_io_fail_tmo is not set.");
>>>  
>> What was the largest timeout value you tried? I think I am hitting a bug
>> with iscsi where if you pass queue_delayed_work a large enough value it
>> will overflow and instead of getting 100 minutes you get 1.
> 
> Well, 0x7fffffff works, 0xffffffff is rejected with -EINVAL.
> And so should every other value with the top bit set.
> 

If someone did 0x7fffffff, then we do 0x7fffffff * HZ in

fc_queue_devloss_work(shost, &rport->dev_loss_work, timeout * HZ);

on a 32bit box, it won't overflow to the value the user wanted will it? 
I think it will not happen normally, but users will try it like they 
have with iscsi and they will end up not knowing how to set it really high.