Re: [dpdk-dev] [PATCH v3] app/testpmd: fix testpmd packets dump overlapping

["Jiawei(Jonny) Wang" <jiaweiw@nvidia.com>]

Hi Ferruh,

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Monday, November 23, 2020 6:23 PM
> To: Jiawei(Jonny) Wang <jiaweiw@nvidia.com>; wenzhuo.lu@intel.com;
> beilei.xing@intel.com; bernard.iremonger@intel.com; Ori Kam
> <orika@nvidia.com>; Slava Ovsiienko <viacheslavo@nvidia.com>; NBU-
> Contact-Thomas Monjalon <thomas@monjalon.net>; Raslan Darawsheh
> <rasland@nvidia.com>
> Cc: dev@dpdk.org
> Subject: Re: [PATCH v3] app/testpmd: fix testpmd packets dump overlapping
> 
> On 11/23/2020 6:13 AM, Jiawei(Jonny) Wang wrote:
> > Hi Ferruh,
> >
> >> -----Original Message-----
> >> From: Ferruh Yigit <ferruh.yigit@intel.com>
> >> Sent: Saturday, November 21, 2020 1:50 AM
> >> To: Jiawei(Jonny) Wang <jiaweiw@nvidia.com>; wenzhuo.lu@intel.com;
> >> beilei.xing@intel.com; bernard.iremonger@intel.com; Ori Kam
> >> <orika@nvidia.com>; Slava Ovsiienko <viacheslavo@nvidia.com>; NBU-
> >> Contact-Thomas Monjalon <thomas@monjalon.net>; Raslan Darawsheh
> >> <rasland@nvidia.com>
> >> Cc: dev@dpdk.org
> >> Subject: Re: [PATCH v3] app/testpmd: fix testpmd packets dump
> >> overlapping
> >>
> >> On 11/20/2020 5:35 PM, Jiawei Wang wrote:
> >>> When testpmd enabled the verbosity for the received packets, if two
> >>> packets were received at the same time, for example, sampling packet
> >>> and normal packet, the dump output of these packets may be
> >>> overlapping due to multiple core handling the multiple queues
> simultaneously.
> >>>
> >>> The patch uses one string buffer that collects all the packet dump
> >>> output into this buffer and then printouts it at last, that
> >>> guarantees to printout separately the dump output per packet.
> >>>
> >>> Fixes: d862c45 ("app/testpmd: move dumping packets to a separate
> >>> function")
> >>>
> >>> Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
> >>
> >> <...>
> >>
> >>> @@ -74,13 +85,16 @@
> >>>    	uint32_t vx_vni;
> >>>    	const char *reason;
> >>>    	int dynf_index;
> >>> +	int buf_size = MAX_STRING_LEN;
> >>> +	char print_buf[buf_size];
> >>> +	int cur_len = 0;
> >>>
> >>> +	memset(print_buf, 0, sizeof(print_buf));
> >>
> >> Should 'print_buf' cleaned per each packet below, if not can we drop
> 'memset'
> >> completely?
> >>
> > Since the 'snprintf' always append the a terminating null
> > character('\0') after the written string, and in the code the
> > following character be appended start from previous null character, so only
> one '\0' will be appended in the last 'snprintf' calls,
> > 	snprintf(buf + cur_len, buf_size - cur_len ..
> > At the last 'printf("%s") will print the string buffer up to a terminating null
> character ('\0').
> > so it's ok even not 'memset' calls to clean 'print_buf' per each packets.
> 
> agree, so why not drop the memset completely?
Yes, don't need memset before 'snprintf' calls, removed it in the latest patch: https://patchwork.dpdk.org/patch/84465/
Thanks.