Re: [PATCH 1/7] print eh activation

[Bernd Schubert <bs@q-leap.de>]

On Wednesday 26 November 2008 19:47:02 James Bottomley wrote:
> On Wed, 2008-11-26 at 18:44 +0100, Bernd Schubert wrote:
> > Print activation of the scsi error handler to let the user know what was
> > the the error handler was activated. These information are essential to
> > diagnose hardware issues.
>
> But it can be turned on already with SCSI logging ... at least the
> activation message.  I don't think we want this to be printed all the
> time, because the error handler can be activated in non-error situations
> for some HBAs (like sense collection for non-ACA emulating drivers).

Sorry for the late reply, I didn't have access to my mails for a few days. 

Actually I entirely disagree, activating the error handler should be an 
exception and as such exception, it shall print it was activated and also the 
reason why it was activated. Without these information we see quite often in 
our logs something like:

[12165690.357905] mptscsih: ioc1: attempting task abort! (sc=ffff81012a957500)
[12165690.357966] sd 3:0:1:0:
[12165690.358018]         command: cdb[0]=0x28: 28 00 37 10 e9 4f 00 00 08 00
[12165690.732712] mptbase: ioc1: IOCStatus(0x0048): SCSI Task Terminated
[12165690.733699] mptscsih: ioc1: task abort: SUCCESS (sc=ffff81012a957500)

But this gives you no chance to see, where it comes from. After adding the 
additional printks from my patch, we recognized the error handler was 
activated mostly due to command timeouts. So increasing the timeouts to >90s 
already solved 2/3rds of our problems. Please also see patch nr. 6, the 
additional printks did help me to recognize always only one special scsi 
command fails.

In my opinion, if a driver needs the error handler for specific actions, we 
should create another interface for that. Could you please point me to such a 
non-ACA river?
I also only see two calling functions of scsi_eh_scmd_add(), namely 
scsi_times_out() and scsi_softirq_done() and only for these calls the 
additinal printks will be done (since scmd is required to do the printks).

Thanks,
Bernd

-- 
Bernd Schubert
Q-Leap Networks GmbH