linux-kernel - Re: [PATCH 6/9] perf record: Support synthesizing cgroup events

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Message-ID: <20200108221833.GD12995@krava>
Date:   Wed, 8 Jan 2020 23:18:33 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Stephane Eranian <eranian@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 6/9] perf record: Support synthesizing cgroup events

On Tue, Jan 07, 2020 at 10:34:58PM +0900, Namhyung Kim wrote:

SNIP

> +	if (perf_tool__process_synth_event(tool, event, machine, process) < 0) {
> +		pr_debug("process synth event failed\n");
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
> +static int perf_event__walk_cgroup_tree(struct perf_tool *tool,
> +					union perf_event *event,
> +					char *path, size_t mount_len,
> +					perf_event__handler_t process,
> +					struct machine *machine)
> +{
> +	size_t pos = strlen(path);
> +	DIR *d;
> +	struct dirent *dent;
> +	int ret = 0;
> +
> +	if (perf_event__synthesize_cgroup(tool, event, path, mount_len,
> +					  process, machine) < 0)
> +		return -1;
> +
> +	d = opendir(path);
> +	if (d == NULL) {
> +		pr_debug("failed to open directory: %s\n", path);
> +		return -1;
> +	}
> +
> +	while ((dent = readdir(d)) != NULL) {
> +		if (dent->d_type != DT_DIR)
> +			continue;
> +		if (!strcmp(dent->d_name, ".") ||
> +		    !strcmp(dent->d_name, ".."))
> +			continue;
> +
> +		if (path[pos - 1] != '/')
> +			strcat(path, "/");
> +		strcat(path, dent->d_name);

shouldn't you also check for the max size of path in here?

jirka