Re: [PATCH] remove name length check in a workqueue

[Frederic TEMPORELLI - astek <ftemporelli@astek.fr>]

James Bottomley a écrit :

>Well, but the other alternative is that we hit arbitrary BUG_ON() limits
>in systems that create numbered workqueues which is rather contrary to
>our scaleability objectives, isn't it?
>
>I think I'd rather the name truncation than have to respond to kernel
>BUG()'s.  If someone really has a problem with the appearance of ps,
>they can always increase TASK_COMM_LEN.
>
>  
>
>>We could truncate the name before adding the CPU number, but it sounds
>>saner to just prevent anyone passing in excessively long names.  Via
>>BUG_ON, say ;)
>>
>>What's the actual problem?
>>    
>>
>
>What I posted originally; the current SCSI format for a workqueue:
>scsi_wq_%d hits the bug after the host number rises to 100, which has
>been seen by some enterprise person with > 100 HBAs.
>
>The reason for this name is that the error handler thread is called
>scsi_eh_%d; so we could rename all our threads to avoid this, but one
>day someone will come along with a huge enough machine to hit whatever
>limit we squeeze it down to.
>
>James
>
>  
>
In scsi layer (drivers/scsi/hosts.c), wq name length is limited to 
KOBJ_NAME_LEN due to the snprintf .
may be nice to use same limit if BUG_ON is kept... but why NULL isn't 
returned, then ?  ;-)

--
Tempo