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

Bjorn Andersson
2019-10-29T05:46:25Z

On Mon 28 Oct 19:37 PDT 2019, cang@codeaurora.org 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