[9065] in linux-scsi channel archive
Re: Can we change the SCSI command timeout?
daemon@ATHENA.MIT.EDU (Eric Youngdale)
Thu Jun 22 22:34:29 2000
Message-ID: <010e01bfdcbb$91cd2900$0f17a8c0@eric.home>
From: "Eric Youngdale" <eric@andante.org>
To: "Douglas Gilbert" <dgilbert@interlog.com>,
"Ricky Beam" <jfbeam@bluetopia.net>
Cc: "Stanley Wu" <wudragon2@yahoo.com>,
"Linux SCSI list" <linux-scsi@vger.rutgers.edu>
Date: Thu, 22 Jun 2000 22:34:33 -0400
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----- Original Message -----
From: "Douglas Gilbert" <dgilbert@interlog.com>
To: "Ricky Beam" <jfbeam@bluetopia.net>
Cc: "Stanley Wu" <wudragon2@yahoo.com>; "Linux SCSI list"
<linux-scsi@vger.rutgers.edu>
Sent: Wednesday, June 14, 2000 11:34 PM
Subject: Re: Can we change the SCSI command timeout?
> I tried to add some logic to the mid level driver [core] so that the
> upper level drivers (specifically sg under superuser's instruction)
> could request a SCSI bus/device/host reset. Basically the patch was
> rejected because it might interfere with the mid level's error
> processing.
I thought we worked through all of those issues. I thought we were
going to add a hook
to let the error handling thread perform the reset - this would take care of
the synchronization
with any other devices on the bus that might be active at the time.
> My feeling is that in some contexts [best known to a user application
> or an upper level driver] turning off the mid level's error processing
> might be advantageous. There is also no way for an application or an
> upper level driver to abort a SCSI command in progress. This means
> that an application can't set an extremely long timeout to the SCSI
> subsystem, run its own timer, and if that timer expires, abort the
> outstanding command.
The context would also be only known to the administrator who is
attempting
to use the feature. Even if the bus is temporarily idle, a bus reset can
change state for a device
(i.e. cause a tape drive to retension), so you really have to pay attention
to what you are doing.
-Eric
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