This commit adds cgroup v2 support to cgroup_init(). With these
changes, cgget and cgset now work on a cgroup v1 mount, a cgroup
v2 mount, or a cgroup v2 unified mount hierarchy.
Signed-off-by: Tom Hromatka <tom.hroma...@oracle.com>
---
src/api.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 106 insertions(+)
diff --git a/src/api.c b/src/api.c
index 2ced9298a275..bb3a86ef8305 100644
--- a/src/api.c
+++ b/src/api.c
@@ -63,6 +63,12 @@ static __thread char errtext[MAXLEN];
/* Task command name length */
#define TASK_COMM_LEN 16
+/* cgroup v2 controllers file */
+#define CGV2_CONTROLLERS_FILE "cgroup.controllers"
+
+/* maximum line length when reading the cgroup.controllers file */
+#define LL_MAX 100
+
/* Check if cgroup_init has been called or not. */
static int cgroup_initialized;
@@ -1148,6 +1154,96 @@ out:
return ret;
}
+/**
+ * Process a cgroup v2 mount and add it to cg_mount_table if it's not a
+ * duplicate.
+ *
+ * @param ent File system description of cgroup mount being processed
+ * @param mnt_tbl_idx cg_mount_table index
+ */
+static int cgroup_process_v2_mnt(struct mntent *ent, int *mnt_tbl_idx)
+{
+ char cgroup_controllers_path[FILENAME_MAX];
+ char *ret_c = NULL, line[LL_MAX], *stok_buff = NULL;
+ int ret = 0, i, duplicate;
+ FILE *fp = NULL;
+
+ /* determine what v2 controllers are available on this mount */
+ snprintf(cgroup_controllers_path, FILENAME_MAX, "%s/%s", ent->mnt_dir,
+ CGV2_CONTROLLERS_FILE);
+
+ fp = fopen(cgroup_controllers_path, "re");
+ if (!fp) {
+ ret = ECGOTHER;
+ goto out;
+ }
+
+ ret_c = fgets(line, LL_MAX, fp);
+ if (ret_c == NULL) {
+ ret = ECGEOF;
+ goto out;
+ }
+
+ /* remove the trailing newline */
+ ret_c[strlen(ret_c) - 1] = '\0';
+
+ /*
+ * cgroup.controllers returns a list of available controllers in
+ * the following format:
+ * cpuset cpu io memory pids rdma
+ */
+ stok_buff = strtok(ret_c, " ");
+ while (stok_buff) {
+ /* do not have duplicates in mount table */
+ duplicate = 0;
+
+ for (i = 0; i < *mnt_tbl_idx; i++) {
+ if (strncmp(cg_mount_table[i].name, stok_buff,
+ FILENAME_MAX) == 0) {
+ duplicate = 1;
+ break;
+ }
+ }
+
+ if (duplicate) {
+ cgroup_dbg("controller %s is already mounted on %s\n",
+ stok_buff, cg_mount_table[i].mount.path);
+
+ ret = cg_add_duplicate_mount(&cg_mount_table[i],
+ ent->mnt_dir);
+ if (ret)
+ goto out;
+
+ /* advance to the next controller */
+ stok_buff = strtok(NULL, " ");
+ continue;
+ }
+
+ /* this controller is not in the mount table. add it */
+ strncpy(cg_mount_table[*mnt_tbl_idx].name,
+ stok_buff, FILENAME_MAX);
+ cg_mount_table[*mnt_tbl_idx].name[FILENAME_MAX-1] = '\0';
+ strncpy(cg_mount_table[*mnt_tbl_idx].mount.path,
+ ent->mnt_dir, FILENAME_MAX);
+ cg_mount_table[*mnt_tbl_idx].mount.path[FILENAME_MAX-1] =
+ '\0';
+ cg_mount_table[*mnt_tbl_idx].version = CGROUP_V2;
+ cg_mount_table[*mnt_tbl_idx].mount.next = NULL;
+ cgroup_dbg("Found cgroup option %s, count %d\n",
+ stok_buff, *mnt_tbl_idx);
+ (*mnt_tbl_idx)++;
+
+ /* advance to the next controller */
+ stok_buff = strtok(NULL, " ");
+ }
+
+out:
+ if (fp)
+ fclose(fp);
+
+ return ret;
+}
+
/**
* cgroup_init(), initializes the MOUNT_POINT.
*
@@ -1256,6 +1352,16 @@ int cgroup_init(void)
if (ret)
goto unlock_exit;
}
+ else if (strcmp(ent->mnt_type, "cgroup2") == 0) {
+ ret = cgroup_process_v2_mnt(ent, &found_mnt);
+ if (ret == ECGEOF)
+ /* The controllers file was empty. Ignore and
+ * move on.
+ */
+ continue;
+ else if (ret)
+ goto unlock_exit;
+ }
}
free(temp_ent);
--
2.25.3
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