linux-kernel - Re: [PATCH] firewire: fw-sbp2: don't retry login or reconnect after unplug

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Message-Id: <200801281126.39620.jwilson@redhat.com>
Date:	Mon, 28 Jan 2008 11:26:39 -0500
From:	Jarod Wilson <jwilson@...hat.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	linux1394-devel@...ts.sourceforge.net,
	Kristian Høgsberg <krh@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: fw-sbp2: don't retry login or reconnect after unplug

On Sunday 27 January 2008 01:14:44 pm Stefan Richter wrote:
> If a device is being unplugged while fw-sbp2 had a login or reconnect on
> schedule, it would take about half a minute to shut the fw_unit down:
>
> Jan 27 18:34:54 stein firewire_sbp2: logged in to fw2.0 LUN 0000 (0
> retries) <unplug>
> Jan 27 18:34:59 stein firewire_sbp2: sbp2_scsi_abort
> Jan 27 18:34:59 stein scsi 25:0:0:0: Device offlined - not ready after
> error recovery Jan 27 18:35:01 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:06 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:12 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:17 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:22 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:27 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:32 stein firewire_sbp2: orb reply timed out,
> rcode=0x11 Jan 27 18:35:32 stein firewire_sbp2: failed to login to fw2.0
> LUN 0000 Jan 27 18:35:32 stein firewire_sbp2: released fw2.0
>
> After this patch, typically only a few seconds spent in __scsi_add_device
> remain:
>
> Jan 27 19:05:50 stein firewire_sbp2: logged in to fw2.0 LUN 0000 (0
> retries) <unplug>
> Jan 27 19:05:56 stein firewire_sbp2: sbp2_scsi_abort
> Jan 27 19:05:56 stein scsi 33:0:0:0: Device offlined - not ready after
> error recovery Jan 27 19:05:56 stein firewire_sbp2: released fw2.0
>
> The benefit of this is negligible on simple setups.  But on buses with
> several devices, we should avoid any unnecessary blockade of fw-sbp2's
> workqueue thread.
>
> Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>

Looks good, makes sense to me, I've hit this one a few times myself. Even if 
we do end up still having the workqueue sleep time, nuking all the 
unnecessary spew and saving a few cycles is definitely worth it.

Signed-off-by: Jarod Wilson <jwilson@...hat.com>


-- 
Jarod Wilson
jwilson@...hat.com
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