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