Re: [PATCH 1/7] print eh activation

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

On Wed, 2008-12-03 at 12:19 +0100, Bernd Schubert wrote:
> 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.

But surely what you're arguing for then, is a printk on command timeout?

> 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).

Mostly we converted the in-use drivers, but things like the parallel
port drivers still use this mechanism.

James