linux-kernel - Re: [PATCH 2/7] perf/cgroup: order events in RB tree by cgroup id

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 8 Jul 2019 17:45:28 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 2/7] perf/cgroup: order events in RB tree by cgroup id

On Mon, Jul 01, 2019 at 11:59:50PM -0700, Ian Rogers wrote:
> +perf_event_groups_first(struct perf_event_groups *groups, int cpu,
> +			struct cgroup *cgrp)
>  {
>  	struct perf_event *node_event = NULL, *match = NULL;
>  	struct rb_node *node = groups->tree.rb_node;
> +#ifdef CONFIG_CGROUP_PERF
> +	int node_cgrp_id, cgrp_id = 0;
> +
> +	if (cgrp)
> +		cgrp_id = cgrp->id;
> +#endif

Is 0 ever a valid cgroup.id ? If so, should we perhaps use -1 to denote
'none' ? Ether way around a little comment here couldn't hurt, saves one
from digging into the cgroup code.