Re: [bug report] Patch "perf tools: Fix pattern matching for same substring in different pmu type" broken

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Jul 19, 2021 at 03:13:06PM +0100, John Garry escreveu:
> Hi guys,
> 
> The named patch has broken PMU alias matching on my arm64 system.

Hi Jin, can you please address this report? Otherwise I'll have to
revert the patch in my next pull req to Linus :-\

- Arnaldo
 
> Specifically it is broken for when multiple tokens are used in the alias.
> For example, alias "hisi_sccl,l3c" would previously match for PMU
> "hisi_sccl3_l3c7", but that no longer works.
> 
> In my example, in looking at the code, the callchain
> pmu_uncore_alias_match("hisi_sccl,l3c", "hisi_sccl3_l3c7") ->
> per_pmu__valid_suffix("hisi_sccl3_l3c7", "hisi_sccl") fails in the following
> check:
> 
> static bool perf_pmu__valid_suffix(char *pmu_name, char *tok)
> {
> 	char *p;
> 	...
> 	p = pmu_name + strlen(tok);
> 	...
> 	if (*p != '_') //here
> 		return false;
> }
> 
> This check assumes the first token must be followed by a '_', but it is
> possibly a numeric.
> 
> Please let me know how this should work. Previously it would match on the
> tokens, ignoring numerics and '_'.
> 
> As an aside, I'll look at why our testcases don't cover this scenario and
> look to add a test if necessary.
> 
> Thanks,
> john
> 
> Ps, please cc linux-perf-users@vger.kernel.org as in the MAINTAINERS file in
> future, as not all subscribe to the open kernel list (and so cannot easily
> reply directly).
> 

-- 

- Arnaldo