From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Stephane Eranian <eranian@google.com>,
Ian Rogers <irogers@google.com>, Andi Kleen <ak@linux.intel.com>
Subject: [PATCH 1/3] tools/lib/fs: Prefer cgroup v1 path
Date: Wed, 16 Dec 2020 18:05:54 +0900 [thread overview]
Message-ID: <20201216090556.813996-1-namhyung@kernel.org> (raw)
The cgroupfs_find_mountpoint() looks up the /proc/mounts file to find
a directory for the given cgroup subsystem. It keeps both cgroup v1
and v2 path since there's a possibility of the mixed hierarchly.
But we can simply use v1 path if it's found as it will override the v2
hierarchy.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/lib/api/fs/cgroup.c | 34 +++++++++++++++-------------------
1 file changed, 15 insertions(+), 19 deletions(-)
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
index 889a6eb4aaca..813236d8ca48 100644
--- a/tools/lib/api/fs/cgroup.c
+++ b/tools/lib/api/fs/cgroup.c
@@ -12,7 +12,7 @@ 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_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
+ char path_v2[PATH_MAX + 1];
char *token, *saved_ptr = NULL;
fp = fopen("/proc/mounts", "r");
@@ -22,45 +22,41 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
/*
* in order to handle split hierarchy, we need to scan /proc/mounts
* and inspect every cgroupfs mount point to find one that has
- * perf_event subsystem
+ * the given subsystem. If we found v1, just use it. If not we can
+ * use v2 path as a fallback.
*/
- path_v1[0] = '\0';
path_v2[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) {
- if (!path_v1[0] && !strcmp(type, "cgroup")) {
+ if (!strcmp(type, "cgroup")) {
token = strtok_r(tokens, ",", &saved_ptr);
while (token != NULL) {
if (subsys && !strcmp(token, subsys)) {
- strcpy(path_v1, mountpoint);
- break;
+ /* found */
+ fclose(fp);
+
+ if (strlen(mountpoint) < maxlen) {
+ strcpy(buf, mountpoint);
+ return 0;
+ }
+ return -1;
}
token = strtok_r(NULL, ",", &saved_ptr);
}
}
- if (!path_v2[0] && !strcmp(type, "cgroup2"))
+ if (!strcmp(type, "cgroup2"))
strcpy(path_v2, mountpoint);
-
- if (path_v1[0] && path_v2[0])
- break;
}
fclose(fp);
- if (path_v1[0])
- path = path_v1;
- else if (path_v2[0])
- path = path_v2;
- else
- return -1;
-
- if (strlen(path) < maxlen) {
- strcpy(buf, path);
+ if (path_v2[0] && strlen(path_v2) < maxlen) {
+ strcpy(buf, path_v2);
return 0;
}
return -1;
--
2.29.2.684.gfbc64c5ab5-goog
next reply other threads:[~2020-12-16 9:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 9:05 Namhyung Kim [this message]
2020-12-16 9:05 ` [PATCH 2/3] tools/lib/fs: Diet cgroupfs_find_mountpoint() Namhyung Kim
2020-12-28 8:31 ` Jiri Olsa
2020-12-29 5:27 ` Namhyung Kim
2020-12-29 9:39 ` Jiri Olsa
2020-12-16 9:05 ` [PATCH 3/3] tools/lib/fs: Cache cgroupfs mount point Namhyung Kim
2020-12-29 11:51 ` Arnaldo Carvalho de Melo
2021-01-06 1:33 ` Namhyung Kim
2021-01-08 5:51 ` Namhyung Kim
2021-01-21 4:33 ` Namhyung Kim
2021-02-17 12:58 ` Arnaldo Carvalho de Melo
2021-02-19 10:05 ` Namhyung Kim
2021-02-19 11:37 ` Arnaldo Carvalho de Melo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201216090556.813996-1-namhyung@kernel.org \
--to=namhyung@kernel.org \
--cc=acme@kernel.org \
--cc=ak@linux.intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=eranian@google.com \
--cc=irogers@google.com \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).