Re: [PATCH v4 07/10] watchdog: wdt-uclass.c: handle all DM watchdogs in watchdog_reset()

Tom Rini
2021-08-17T12:35:21Z

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On Tue, Aug 17, 2021 at 11:28:39AM +0200, Stefan Roese wrote:
> On 12.08.21 15:48, Tom Rini wrote:
> > On Thu, Aug 12, 2021 at 08:40:21AM +0200, Wolfgang Denk wrote:
> > > Dear Tom,
> > >
> > > In message <20210811124318.GT858@bill-the-cat> you wrote:
> > > >
> > > > > This argument fits on all types or effors: they are supposed to
> > > > > never ever happen - at least in theory; in reality they do, and more
> > > > > often than we like.
> > > > >
> > > > > And a proper error message is mandatory for correct error handling.
> > > >
> > > > Error messages are a fine line to walk. We've got to have been very
> > > > badly corrupted to go down this error path. There's going to be lots of
> > > > other error messages popping out. Saving a bit of .text is good. It
> > > > makes it easier to justify spending a little .text later.
> > >
> > > Letting errors slip through unnoticed when there is a trival way to
> > > at least inform the user of the problem is simply unacceptable.
> > >
> > > Please do not let U-Boot degrade into such a crappy piece of code.
> > >
> > > There are tons of other places where we don't even mention code
> > > size, so if you want to save on that, there are many bette4r places
> > > to save than error handling.
> >
> > Alright, lets take a look at what kind of area of the code we're talking
> > about. uclass_get is a pretty fundamental thing. If that fails, your
> > system is on fire. Things are massively corrupt. Lets look at other
> > existing callers to see what happens. Most callers check the return
> > code, like you need to, and pass it up the chain to deal with. We have
> > a few board specific ones such as
> > board/Marvell/octeontx2/board.c::board_quiesce_devices() that is also
> > conceptually like the x530 case in the next part of the series. That
> > does print on failure. The rest of the ones that print an error message
> > are about commands and it's somewhat helpful there.
> >
> > So yes, return codes need to be checked and passed. But no, not every
> > single error path needs to print to the user along every part of an
> > error path either.
> >
> > > > And here I agree, catch an error code, pass the error code back to the
> > > > caller. That's far more important than making sure that every error
> > > > code we catch logs a message by default every time.
> > >
> > > It does not matter where the error is reported - in the called
> > > function, or in some caller firther up the call tree. But it _must_
> > > be reportet at least once.
> > >
> > > So if we don't issue an error message here, we need to check and fix
> > > the callers, too.
> >
> > That would be the next patch in the series where the BSP author isn't
> > currently checking the return value, and this series doesn't change
> > that. Perhaps it should, and CC the maintainer. But I think has been
> > said a few times over the course of this series, what exactly is one
> > going to do about the failure? Getting specific for a moment, if you're
> > in the case of "shutdown the watchdog" and the watchdog doesn't shutdown
> > like you want it to, do you hang and hope the watchdog is alive to kick
> > things still? hang and lock the system? Figure the system is on fire
> > anyhow but add another message to the failure spew?
> >
> > Again, I think the change that's needed to this patch is to make it
> > return the error code to the caller. Let the caller decide. And make
> > sure to CC the board maintainer on the next go-round so they can chime
> > in about that.
>
> Getting back to this to hopefully get this decided:
>
> It seems that we (most of us?) agree on this change, that wdt_stop_all()
> shall be changed to return an error code and the caller can decide what
> to do with it?
>
> If yes, then Rasmus, could you please re-spin this patchset accordingly
> and send v6?

Yes, please and thanks.

--
Tom

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