RE: [RFC 2/5] net/ngbe: fix query handling in xstats_get

["Zaiyu Wang" <zaiyuwang@trustnetic.com>]

> 
> Cc: Zaiyu Wang <zaiyuwang@net-swift.com>
> 
> > -----Original Message-----
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: Thursday, December 5, 2024 6:19 AM
> > To: dev@dpdk.org
> > Cc: jiawenwu@trustnetic.com
> > Subject: Re: [RFC 2/5] net/ngbe: fix query handling in xstats_get
> >
> > On Tue,  8 Oct 2024 08:59:56 -0700
> > Stephen Hemminger <stephen@networkplumber.org> wrote:
> >
> > > The xstats_get function in this driver did not act the same as other
> > > drivers when queried. The correct check is to look at the requested
> > > number of stats and compare it to the available stats and if the
> > > request is too small, return the correct size.
> > >
> > > Bugzilla ID: 1560
> > > Fixes: 8b433d04adc9 ("net/ngbe: support device xstats")
> > > Cc: jiawenwu@trustnetic.com
> > >
> > > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> >
> > This needs to be tested on this hardware before merging.
> >
> 
Hi Stephen Hemminger,

We have tested this patch for ngbe&txgbe driver with the corresponding
hardware.
But this patch can't fix the bug reported in Bugzilla. In fact, most
applications,
including telemetry, call rte_eth_xstats_get twice, fist to get num of
xstats and then
to get the full xstats data.

This bug appeared after dpdk-22.11 because rte_tel_data_add_dict_string
restricted
the characters in dicts, and '[' and ']' were no longer allowed to be used,
so ngbe&txgbe
could not print xstats by telemetry. 

For more details about this restriction, please see:
https://patches.dpdk.org/project/dpdk/patch/20220909093523.471727-2-bruce.ri
chardson@intel.com/

And here is the code in ngbe for setting xstats name, which add '[' and ']'
in them:

static inline int
ngbe_get_name_by_id(uint32_t id, char *name, uint32_t size)
{
...
	if (id < NGBE_NB_HW_STATS) {
		snprintf(name, size, "[hw]%s",
			rte_ngbe_stats_strings[id].name);
		return 0;
	}

To save this issue, could we add '[' and ']' to the allowed characters of
telemetry? Or we
must change the xstats name in ngbe&txgbe driver?	

Thanks.