Re: [PATCH] SCSI: increase default timeout for INQUIRY

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Thu, 2009-03-12 at 09:12 -0600, Matthew Wilcox wrote:
> On Thu, Mar 12, 2009 at 11:08:51AM -0400, Alan Stern wrote:
> > It's hard to see how this could cause any signficant problems, unless 
> > somebody actually depends on INQUIRY timing out.
> 
> Erm, like doing a scan of a bus?  With 15 devices to probe, you've
> increased the time from 15 * 3 = 45 seconds to 15 * 20 = 300 seconds.
> That's not cool ;-(
> 
> Maybe we could default this in the transport or something so USB can
> override it.

Well, no, this is the overall command timeout.  Each bus (that's
scannable) has its own timeout.  For instance, on a parallel bus this is
250ms per device ... don't respond in that time, we return
DID_NO_CONNECT.

I think what Alan is saying is that some USB devices will take >5s to
respond to an initial inquiry.  Remember that USB isn't actually a
scannable bus.  We get told there's a device there and we have to send
an INQUIRY to classify it.

James