Re: [PATCH bpf-next v7 4/6] selftests/bpf: Adjust veristat stack depth parsing

[Eduard Zingerman <eddyz87@gmail.com>]

On Sat, 2026-08-08 at 08:25 +0200, Kumar Kartikeya Dwivedi wrote:
> The verifier now reports instruction and stack depth statistics using
> uniform "subprog <id> (<name>) <kind>" records. Subprogram 0 is classified
> as main, while other records are global or static. Each record carries
> insns_self, insns_total, and stack depth.
> 
> Teach veristat to parse the new records while retaining support for the
> legacy one-line stack depth format used by older kernels. Skip both
> instruction counts and match only through the stack value so fields can
> still be appended without breaking parsing.
> 
> Increase the bounded backward scan so it can include all 256 per-subprogram
> records.
> 
> Zero-initialize the legacy stack buffer because logs using the new format do
> not populate it before the trailing tokenizer loop. This makes the loop see
> an empty string instead of reading uninitialized data.
> 
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

> @@ -1025,11 +1027,17 @@ static int parse_verif_log(char * const buf, size_t buf_sz, struct verif_stats *
>  				&s->stats[MARK_READ_MAX_LEN]))
>  			continue;
>  
> +		if (sscanf(cur, "stack depth max %ld", &s->stats[MAX_STACK]) == 1)
> +			continue;
> +		if (sscanf(cur, "subprog %*d %*s %*s insns_self %*d insns_total %*d stack %ld", &sub_stack) == 1) {
> +			s->stats[STACK] += sub_stack;
> +			continue;
> +		}

Nit: a comment about why two different formats are matched would be helpful.

>  		if (2 == sscanf(cur, "stack depth %511s max %ld", stack, &s->stats[MAX_STACK]))
>  			continue;
>  	}
>  	while ((token = strtok_r(cnt++ ? NULL : stack, "+", &state))) {
> -		if (sscanf(token, "%d", &sub_stack) == 0)
> +		if (sscanf(token, "%ld", &sub_stack) == 0)
>  			break;
>  		s->stats[STACK] += sub_stack;
>  	}