Re: [PATCH v1 1/1] scsi: ufs: Add command logging infrastructure

[Bjorn Andersson]

On Mon 28 Oct 19:37 PDT 2019, cang@xxxxxxxxxxxxxx wrote:

> On 2019-10-23 18:33, Avri Altman wrote:
> > > 
> > > > Add the necessary infrastructure to keep timestamp history of
> > > > commands, events and other useful info for debugging complex issues.
> > > > This helps in diagnosing events leading upto failure.
> > > 
> > > Why not use tracepoints, for that?
> > Ack on Tomas's comment.
> > Are there any pieces of information that you need not provided by the
> > upiu tracer?
> > 
> > Thanks,
> > Avri
> 
> In extreme cases, when the UFS runs into bad state, system may crash. There
> may not be a chance to collect trace. If trace is not collected and failure
> is hard to be reproduced, some command logs prints would be very helpful to
> help understand what was going on before we run into failure.
> 

This is a common problem shared among many/all subsystems, so it's
better to rely on a generic solution for this; such as using tracepoints
dumped into pstore/ramoops.

Regards,
Bjorn