On Tue 05 Dec 02:54 PST 2017, Arnaud Pouliquen wrote:
>
>
> On 12/05/2017 07:46 AM, Bjorn Andersson wrote:
> > On Fri 01 Dec 06:50 PST 2017, Arnaud Pouliquen wrote:
> >
> >> hello Bjorn,
> >>
> >> Sorry for these late remarks/questions
> >>
> >
> > No worries, I'm happy to see you reading the patch!
> >
> >>
> >> On 11/30/2017 02:16 AM, Bjorn Andersson wrote:
> > [..]
> >>> diff --git a/drivers/remoteproc/qcom_common.c b/drivers/remoteproc/qcom_common.c
> > [..]
> >>> @@ -785,17 +785,17 @@ static int rproc_probe_subdevices(struct rproc *rproc)
> >>>
> >>> unroll_registration:
> >>> list_for_each_entry_continue_reverse(subdev, &rproc->subdevs, node)
> >>> - subdev->remove(subdev);
> >>> + subdev->remove(subdev, false);
> >> Why do you need to do a non graceful remove in this case? This could
> >> lead to side effect like memory leakage...
> >>
> >
> > Regardless of this being true or false resources should always be
> > reclaimed.
> >
> > The reason for introducing this is that the modem in the Qualcomm
> > platforms implements persistent storage and it's preferred to tell it to
> > flush the latest data to the storage server (on the Linux side) before
> > pulling the plug. But in the case of a firmware crash this mechanism
> > will not be operational and there's no point in attempting this
> > "graceful shutdown".
> I understand your usecase for Qualcomm, but in rproc_probe_subdevices
> there is not crash of the remote firmware , so remove should be graceful.
>
Now I get your point, sorry. I agree with you, as this is triggering a
clean stop of the system this should be marked "graceful".
Will update, thanks.
> >
> > [..]
> >>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> >>> index 44e630eb3d94..20a9467744ea 100644
> >>> --- a/include/linux/remoteproc.h
> >>> +++ b/include/linux/remoteproc.h
> >>> @@ -456,7 +456,7 @@ struct rproc_subdev {
> >>> struct list_head node;
> >>>
> >>> int (*probe)(struct rproc_subdev *subdev);
> >>> - void (*remove)(struct rproc_subdev *subdev);
> >>> + void (*remove)(struct rproc_subdev *subdev, bool graceful);
> >> What about adding a new ops instead of a parameter, like a recovery
> >> callback?
> >>
> >
> > I think that for symmetry purposes it should be probe/remove in both
> > code paths. A possible alternative to the proposal would be to introduce
> > an operation "request_shutdown()" the would be called in the proposed
> > graceful code path.
> >
> >
> > However, in the Qualcomm SMD and GLINK (conceptually equivalent to
> > virtio-rpmsg) it is possible to open and close communication channels
> > and it's conceivable to see that the graceful case would close all
> > channels cleanly while the non-graceful case would just remove the rpmsg
> > devices (and leave the channel states/memory as is).
> >
> > In this case a "request_shutdown()" would complicate things, compared to
> > the boolean.
> >
> I would be more for a specific ops that inform sub-dev on a crash. This
> would allow sub-dev to perform specific action (for instance dump) and
> store crash information, then on remove, sub_dev would perform specific
> action.
There is a separate discussion (although dormant) on how to gather core
dumps, which should cover these cases.
> This could be something like "trigger_recovery" that is propagated to
> the sub-dev.
>
Right, this step does make sense, but is the opposite of what I need -
i.e. a means to trigger a clean shutdown.
> That would sound more flexible from my point of view.
>
At this point I see this flexibility as unnecessary complexity, if such
need show up (beyond the core dump gathering) we should bring this up
again.
Regards,
Bjorn
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