Re: [PATCH v15 04/35] firmware: arm_scmi: Allow registration of unknown-size events/reports

[Cristian Marussi]

On Mon, Nov 09, 2026 at 02:07:36PM -0800, Jonathan Cameron wrote:
> On Mon,  9 Nov 2026 09:11:50 +0000
> Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
> 
> > Allow protocols to register events with build-time unknown sizes: such
> > events can be declared zero-sized and let the core SCMI stack perform the
> > needed safe-net boundary checks based on the configured transport size.
> > 
> > Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxxxxxxxx>
> > Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> > ---
> > v14 --> v15
> >  - better commenting
> 
> A few bits of feedback on the comments.
> 
> > v12 --> v13
> >  - improve variable naming
> > v10 --> v11
> >  - account for ktime_t field when checking boundary
> > v2 --> v3
> >  - split out of previous patch on protocol notifier
> >  - use max() instead of max_t()
> > ---
> >  drivers/firmware/arm_scmi/notify.c | 28 +++++++++++++++++++++++-----
> >  drivers/firmware/arm_scmi/notify.h |  8 ++++++--
> >  2 files changed, 29 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c
> > index bc046f2f83a6..a30589c9b377 100644
> > --- a/drivers/firmware/arm_scmi/notify.c
> > +++ b/drivers/firmware/arm_scmi/notify.c
> > @@ -595,7 +595,16 @@ int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id,
> >  	if (!r_evt)
> >  		return -EINVAL;
> >  
> > -	if (len > r_evt->evt->max_payld_sz) {
> > +	/*
> > +	 * Events with a zero max_payld_sz are sized to be of the maximum
> > +	 * size allowed by the transport: no need to be size-checked here
> > +	 * since the transport layer would have already dropped such
> > +	 * over-sized messages.
> 
> 'such' here to me refers to the first bit. That is, those that are "
> sized to be the maxim size allowed by the transport.
> 
> I'd just drop 'such' and have
> 	 * since the transport layer would have already dropped over-sized
> 	 * messages.
> 
> as that avoids this potential confusion.
> 
> > +	 * Note that, though, while this protects from buffer overruns, it is
> 
> Drop 'though'. Doesn't add anything and leads to odd flow to the sentence
> 
> > +	 * no more possible at this layer of the stack to detect zero-sized
> 
> 'not possible at this layer ..'
> 
> The 'no more' refers to code that isn't here if someone reads this code
> once the patch is merged.  So if you want to refer to what changed, keep
> it in the patch description not a comment.
> 

Thanks...it seems like the more I try to write clear and meaningful
sentences in English the more I mess up :D

Cristian