RE: [net-next v3 13/15] iecm: Add ethtool

["Brady, Alan" <alan.brady@intel.com>]

> -----Original Message-----
> From: Joe Perches <joe@perches.com>
> Sent: Thursday, June 25, 2020 8:29 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com>; davem@davemloft.net
> Cc: Michael, Alice <alice.michael@intel.com>; netdev@vger.kernel.org;
> nhorman@redhat.com; sassmann@redhat.com; Brady, Alan
> <alan.brady@intel.com>; Burra, Phani R <phani.r.burra@intel.com>; Hay,
> Joshua A <joshua.a.hay@intel.com>; Chittim, Madhu
> <madhu.chittim@intel.com>; Linga, Pavan Kumar
> <pavan.kumar.linga@intel.com>; Skidmore, Donald C
> <donald.c.skidmore@intel.com>; Brandeburg, Jesse
> <jesse.brandeburg@intel.com>; Samudrala, Sridhar
> <sridhar.samudrala@intel.com>
> Subject: Re: [net-next v3 13/15] iecm: Add ethtool
> 
> On Thu, 2020-06-25 at 19:07 -0700, Jeff Kirsher wrote:
> > From: Alice Michael <alice.michael@intel.com>
> >
> > Implement ethtool interface for the common module.
> []
> > diff --git a/drivers/net/ethernet/intel/iecm/iecm_ethtool.c
> > b/drivers/net/ethernet/intel/iecm/iecm_ethtool.c
> []
> > +/* Stats associated with a Tx queue */ static const struct iecm_stats
> > +iecm_gstrings_tx_queue_stats[] = {
> > +	IECM_QUEUE_STAT("%s-%u.packets", q_stats.tx.packets),
> > +	IECM_QUEUE_STAT("%s-%u.bytes", q_stats.tx.bytes), };
> > +
> > +static const struct iecm_stats iecm_gstrings_rx_queue_stats[] = {
> > +	IECM_QUEUE_STAT("%s-%u.packets", q_stats.rx.packets),
> > +	IECM_QUEUE_STAT("%s-%u.bytes", q_stats.rx.bytes),
> > +	IECM_QUEUE_STAT("%s-%u.generic_csum", q_stats.rx.generic_csum),
> > +	IECM_QUEUE_STAT("%s-%u.basic_csum", q_stats.rx.basic_csum),
> > +	IECM_QUEUE_STAT("%s-%u.csum_err", q_stats.rx.csum_err),
> > +	IECM_QUEUE_STAT("%s-%u.hsplit_buf_overflow",
> q_stats.rx.hsplit_hbo),
> > +};
> > +
> > +#define IECM_TX_QUEUE_STATS_LEN
> 	ARRAY_SIZE(iecm_gstrings_tx_queue_stats)
> > +#define IECM_RX_QUEUE_STATS_LEN
> 	ARRAY_SIZE(iecm_gstrings_rx_queue_stats)
> > +
> > +/**
> > + * __iecm_add_stat_strings - copy stat strings into ethtool buffer
> > + * @p: ethtool supplied buffer
> > + * @stats: stat definitions array
> > + * @size: size of the stats array
> > + *
> > + * Format and copy the strings described by stats into the buffer
> > +pointed at
> > + * by p.
> > + */
> > +static void __iecm_add_stat_strings(u8 **p, const struct iecm_stats stats[],
> > +				    const unsigned int size, ...) {
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < size; i++) {
> > +		va_list args;
> > +
> > +		va_start(args, size);
> > +		vsnprintf((char *)*p, ETH_GSTRING_LEN,
> > +			  stats[i].stat_string, args);
> > +		*p += ETH_GSTRING_LEN;
> > +		va_end(args);
> > +	}
> > +}
> 
> Slightly dangerous to have a possible mismatch between the varargs and the
> actual constant format spec.
> 
> Perhaps safer to use something like:
> 
> static const struct iecm_stats iecm_gstrings_tx_queue_stats[] = {
> 	IECM_QUEUE_STAT("packets", q_stats.tx.packets),
> 	IECM_QUEUE_STAT("bytes", q_stats.tx.bytes), };
> 
> Perhaps use const char * and unsigned int instead of varargs so this formats the
> output without va_start/end
> 
> 	snprintf(*p, ETH_GSTRING_LEN, "%s-%u.%s", type, index,
> stats[i].stat_string);
> 

Agreed this could be better.  Will rework without varargs.

Alan