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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tkrat.b69dbd0ef9978d09@s5r6.in-berlin.de>
Date:	Sun, 27 Jan 2008 19:26:33 +0100 (CET)
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linux1394-devel@...ts.sourceforge.net
cc:	Jarod Wilson <jwilson@...hat.com>,
	Kristian Høgsberg <krh@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: fw-sbp2: don't retry login or reconnect after
 unplug

I 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.

There is an error in the last sentences.  The time spent sleeping in
workqueue jobs is the same before and after.  What this patch only
avoids are a few wasted CPU cycles, irritating log messages, and
needlessly prolonged lifetime of a few driver objects.

However, less noise in the syslog may already be enough justification
for this patch.
-- 
Stefan Richter
-=====-==--- ---= ==-==
http://arcgraph.de/sr/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/