RE: [PATCH v4 net-next 06/14] net: enetc: add support for the "Update" operation to buffer pool table

[Wei Fang]

> > @@ -702,5 +708,38 @@ int ntmp_vft_add_entry(struct ntmp_user *user,
> u16 vid,
> >  }
> >  EXPORT_SYMBOL_GPL(ntmp_vft_add_entry);
> >
> > +int ntmp_bpt_update_entry(struct ntmp_user *user, u32 entry_id,
> > +			  const struct bpt_cfge_data *cfge)
> > +{
> > +	struct ntmp_dma_buf data = {
> > +		.dev = user->dev,
> > +		.size = sizeof(struct bpt_req_update),
> > +	};
> > +	struct bpt_req_update *req;
> > +	union netc_cbd cbd;
> > +	int err;
> > +
> > +	err = ntmp_alloc_data_mem(&data, (void **)&req);
> > +	if (err)
> > +		return err;
> > +
> > +	ntmp_fill_crd_eid(&req->rbe, user->tbl.bpt_ver, 0,
> > +			  NTMP_GEN_UA_CFGEU | BPT_UA_BPSEU, entry_id);
> 
> Does this update action mask match the size of the request buffer?
> 
> The mask includes both NTMP_GEN_UA_CFGEU and BPT_UA_BPSEU, which
> instructs
> the hardware to update both the configuration entry and the status entry.
> However, struct bpt_req_update only contains the configuration data,
> omitting the status data.
> 
> If the hardware attempts to read the missing BPSE data, could it reject
> the command due to an undersized request length, or read beyond the
> intended payload into zero-initialized DMA padding? This might overwrite
> critical buffer pool tracking variables like amount_used_hwm.
> 
> If only the configuration is being updated, should the BPT_UA_BPSEU flag
> be removed?

The BPSE_DATA is a set of statistics and status records kept by the hardware
(internal buffer), and does not require the user to provide additional data to
the hardware for updates. Therefore, for the 'update' operation, the request
buffer does not need to provide BPSE_DATA data.