Commit 6fd99b7f authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

tools api fs: Diet cgroupfs_find_mountpoint() 



Reduce the number of buffers and hopefully make it more efficient. :)

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201216090556.813996-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 27ab1c1c

tools/lib/api/fs/cgroup.c

+45 −25
Original line number Diff line number Diff line
@@ -11,9 +11,10 @@ 
int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)

{

	FILE *fp;

	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];

	char path_v2[PATH_MAX + 1];

	char *token, *saved_ptr = NULL;

	char *line = NULL;

	size_t len = 0;

	char *p, *path;

	char mountpoint[PATH_MAX];



	fp = fopen("/proc/mounts", "r");

	if (!fp)
@@ -25,38 +26,57 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys) 
	 * the given subsystem.  If we found v1, just use it.  If not we can

	 * use v2 path as a fallback.

	 */

	path_v2[0] = '\0';

	mountpoint[0] = '\0';



	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"

				__stringify(PATH_MAX)"s %*d %*d\n",

				mountpoint, type, tokens) == 3) {

	/*

	 * The /proc/mounts has the follow format:

	 *

	 *   <devname> <mount point> <fs type> <options> ...

	 *

	 */

	while (getline(&line, &len, fp) != -1) {

		/* skip devname */

		p = strchr(line, ' ');

		if (p == NULL)

			continue;



		if (!strcmp(type, "cgroup")) {

		/* save the mount point */

		path = ++p;

		p = strchr(p, ' ');

		if (p == NULL)

			continue;



			token = strtok_r(tokens, ",", &saved_ptr);

		*p++ = '\0';



			while (token != NULL) {

				if (subsys && !strcmp(token, subsys)) {

					/* found */

					fclose(fp);

		/* check filesystem type */

		if (strncmp(p, "cgroup", 6))

			continue;



					if (strlen(mountpoint) < maxlen) {

						strcpy(buf, mountpoint);

						return 0;

					}

					return -1;

				}

				token = strtok_r(NULL, ",", &saved_ptr);

			}

		if (p[6] == '2') {

			/* save cgroup v2 path */

			strcpy(mountpoint, path);

			continue;

		}



		if (!strcmp(type, "cgroup2"))

			strcpy(path_v2, mountpoint);

		/* now we have cgroup v1, check the options for subsystem */

		p += 7;



		p = strstr(p, subsys);

		if (p == NULL)

			continue;



		/* sanity check: it should be separated by a space or a comma */

		if (!strchr(" ,", p[-1]) || !strchr(" ,", p[strlen(subsys)]))

			continue;



		strcpy(mountpoint, path);

		break;

	}

	free(line);

	fclose(fp);



	if (path_v2[0] && strlen(path_v2) < maxlen) {

		strcpy(buf, path_v2);

	if (mountpoint[0] && strlen(mountpoint) < maxlen) {

		strcpy(buf, mountpoint);

		return 0;

	}

	return -1;