Re: [Comments Needed] scan vs remove_target deadlock

[James Smart <James.Smart@Emulex.Com>]

Michael Reed wrote:
> The remove is not for the target which holds the scsi host's scan mutex.
> Hence, the unblock doesn't kick the [right] queue.

Certainly could be true.

> I think this means that transport cannot call scsi_remove_target() for any
> target if a scan is running.  So, transport has to wait until it can assure
> that no scan is running, perhaps a new mutex, and has to have a way of kicking
> a blocked target which is being scanned, either when the LLDD unblocks
> the target or the delete work for that target fires.

Well - that's one way. Very difficult for the transport to know when this is
true (not all scans occur from the transport). It should be a midlayer thing
to ensure the proper things happen. Also highlights just how gross the that
scan_lock is - which is where the real fix should be, although this will be
a rats nest.

-- james s