[dpdk-dev] [EXT] Re: [v5] telemetry: fix json output buffer size

[Gowrishankar Muthukrishnan]

Hi Thomas,

> -----Original Message-----
> From: Thomas Monjalon <thomas at monjalon.net>
> Sent: Wednesday, October 6, 2021 11:09 PM
> To: Gowrishankar Muthukrishnan <gmuthukrishn at marvell.com>
> Cc: dev at dpdk.org; bruce.richardson at intel.com; ciara.power at intel.com; Jerin
> Jacob Kollanukkaran <jerinj at marvell.com>
> Subject: [EXT] Re: [dpdk-dev] [v5] telemetry: fix json output buffer size
> 
> External Email
> 
> ----------------------------------------------------------------------
> 29/09/2021 06:18, Gowrishankar Muthukrishnan:
> > Fix json output buffer size for an actual data length.
> >
> > Fixes: 52af6ccb2b39 ("telemetry: add utility functions for creating
> > JSON")
> 
> Please could you give a bit more explanations?
> What was not working and why?

Without this patch, our driver end point (crypto/cnxk) could not successfully deliver the requested info
due to its larger amount than the fixed buffer length of 1024 bytes as handled by __json_snprintf.
I think it is genuine bug too which we caught up here.

Thanks,
Gowrishankar
> 
> [...]
> > - * This function is not for use for values larger than 1k.
> > + * This function is not for use for values larger than given buffer length.
> >   */
> >  __rte_format_printf(3, 4)
> >  static inline int
> >  __json_snprintf(char *buf, const int len, const char *format, ...)  {
> > -	char tmp[1024];
> > +	char tmp[len];
> >  	va_list ap;
> >  	int ret;
> 
> 
>