linux-kernel - Re: [PATCH 21/21] perf/x86/intel/lbr: Support XSAVES for arch LBR read

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Date:   Mon, 22 Jun 2020 21:49:37 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     kan.liang@...ux.intel.com
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        tglx@...utronix.de, bp@...en8.de, x86@...nel.org,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, dave.hansen@...el.com, yu-cheng.yu@...el.com,
        bigeasy@...utronix.de, hpa@...or.com,
        alexey.budankov@...ux.intel.com, eranian@...gle.com,
        ak@...ux.intel.com, like.xu@...ux.intel.com,
        yao.jin@...ux.intel.com
Subject: Re: [PATCH 21/21] perf/x86/intel/lbr: Support XSAVES for arch LBR
 read

On Fri, Jun 19, 2020 at 07:04:09AM -0700, kan.liang@...ux.intel.com wrote:
...
> +static void intel_pmu_arch_lbr_read_xsave(struct cpu_hw_events *cpuc)
> +{
> +	struct x86_perf_task_context_arch_lbr_xsave *xsave = cpuc->lbr_xsave;
> +	struct arch_lbr_entry *lbr;
> +	int i;
> +
> +	if (!xsave)
> +		goto rollback;

Why not make it simplier?

	if (!xsave) {
		intel_pmu_arch_lbr_read(cpuc);
		return;
	}

The goto and "return" statement before the "rollback" label
looks pretty ugly. I'm sorry I didn't follow the series
in details so if you plan to add more handlers at "rollback"
then sure.