Re: [PATCH] Fix reference counting for failed SCSI devices

Hannes Reinecke
2005-05-25T15:16:41Z

James Bottomley wrote:
> On Wed, 2005-05-25 at 14:46 +0200, Hannes Reinecke wrote:
>>>so it's contained within the scsi_device. Freeing the scsi_device frees
>>>the classdev (and the gendev).
>>>
>>But does not call the ->release function.
>
> Please just read the code like I asked. If you do, you'll find that the
> sdev_classdev release method is NULL until scsi_sysfs_add_sdev()
> precisely for the reason that the class references don't matter until
> that point. We're free to kill the whole thing without bothering about
> the class devices until scsi_add_lun detects something and calls
> scsi_sysfs_add_sdev() to make the whole thing visible. Then all
> classdevs get a ref on the parent gendev which their release method
> relinquishes.
>
Oh, right. Indeed, you are totally correct. Sorry for the noise.

>>Put it the other way round: does 'rmmod aic7xxx' work for you?
>>It certainly did _not_ work for aic79xx, hence the fix.
>
> Well, I know aic7xxx works perfectly on a dual channel card, because I
> actually test the failure paths and insmod/rmmod is one of my tests. I
> can't comment on aic79xx because I don't have the hardware.
>
I guess it's time to convert aic79xx to the spi_transport class.
Unfortunately my attempt segfaults when removing a device in
attribute_container_device_trigger(); someone is overwriting the ->match
function. Oh well, further debugging needed.

Cheers,

Hannes
--
Dr. Hannes Reinecke hare@suse.de
SuSE Linux AG S390 & zSeries
Maxfeldstraße 5 +49 911 74053 688
90409 Nürnberg http://www.suse.de