MFC of "Large set of CAM improvements" breaks I/O to Adaptec 29160 SCSI controller

[Scott Long]

On Apr 27, 2010, at 2:20 PM, Andy Farkas wrote:

> On Wed, Apr 28, 2010 at 6:12 AM, Matthew Jacob <mj at feral.com> wrote:
> 
>> Does anything time out (eventually)?
> 
> No. I left it sitting overnight and it was still deadlocked
> in the morning...
> 

A couple of possible scenarios here:

1.  A command completed with an error, that error was reported up to the periph layer, and the periph failed to properly handle it, leading to a lost command that eventually livelocked the VM/block layer.
2.  An error happened the transport layer, and the aic7xxx tried to freeze the CAM queues to perform error recovery.  Something broke in the freeze/unfreeze API, so the aic7xxx was left stranded.

The more I think about it, it's likely case 2, since I know that Alexander has been working in or near that code.

Scott