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Add cgroup v2 support #133

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124 changes: 108 additions & 16 deletions src/rt-app_taskgroups.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,12 +11,16 @@
#include "rt-app_taskgroups.h"

#define PIN "[tg] "
#define SUBTREE_CONTROL "cgroup.subtree_control"
#define TYPE "cgroup.type"
#define CONTROLLERS "cgroup.controllers"

typedef struct _taskgroup_ctrl_t
{
char *mount_point;
taskgroup_data_t *tg_array;
unsigned int nr_tgs;
char version;
} taskgroup_ctrl_t;

static taskgroup_ctrl_t ctrl;
Expand Down Expand Up @@ -143,6 +147,31 @@ static int cgroup_check_cpu_controller(void)
return ret;
}

static int cgroup_check_cpu_controller_v2(char* mnt_dir)
{
size_t size = strlen(mnt_dir) + strlen(CONTROLLERS) + 2;
char* path = malloc(size);
char buf[256];
FILE *file;
snprintf(path, size, "%s/%s", mnt_dir, CONTROLLERS);
file = fopen(path, "r");
if (!file) {
perror("fopen");
goto error;
}
while (fscanf(file, "%s", buf) != EOF) {
if (!strcmp(buf, "cpu")) {
return 0;
}
}
if (fclose(file)) {
perror("fclose");
goto error;
}
error:
return -1;
}

static int cgroup_get_cpu_controller_mount_point(void)
{
struct mntent *ent;
Expand All @@ -157,23 +186,38 @@ static int cgroup_get_cpu_controller_mount_point(void)
}

while (ent = getmntent(mounts)) {
if (strcmp(ent->mnt_type, "cgroup"))
continue;
if (!strcmp(ent->mnt_type, "cgroup")) {
if (!hasmntopt(ent, "cpu"))
continue;

if (!hasmntopt(ent, "cpu"))
continue;
ctrl.mount_point = malloc(strlen(ent->mnt_dir) + 1);
if (!ctrl.mount_point) {
perror("malloc");
break;
}
ctrl.version = 1;

ctrl.mount_point = malloc(strlen(ent->mnt_dir) + 1);
if (!ctrl.mount_point) {
perror("malloc");
strcpy(ctrl.mount_point, ent->mnt_dir);
log_debug(PIN "cgroup cpu controller mountpoint [%s] found", ent->mnt_dir);
ret = 0;
break;
}
} else if (!strcmp(ent->mnt_type, "cgroup2")) {
if (cgroup_check_cpu_controller_v2(ent->mnt_dir) == -1) {
continue;
}

strcpy(ctrl.mount_point, ent->mnt_dir);
ctrl.mount_point = malloc(strlen(ent->mnt_dir) + 1);
if (!ctrl.mount_point) {
perror("malloc");
break;
}
ctrl.version = 2;

log_debug(PIN "cgroup cpu controller mountpoint [%s] found", ent->mnt_dir);
ret = 0;
break;
strcpy(ctrl.mount_point, ent->mnt_dir);
log_debug(PIN "cgroup cpu controller mountpoint [%s] found", ent->mnt_dir);
ret = 0;
break;
}
}

endmntent(mounts);
Expand Down Expand Up @@ -253,6 +297,24 @@ static int cgroup_mkdir(const char *name, int *offset)
} else if (*offset == -1) {
*offset = y;
}

if (ctrl.version == 2) {
size_t path_size = strlen(path) + strlen(SUBTREE_CONTROL) + 2;
char* cgroup_path = malloc(path_size);
FILE *cgroup_file;
snprintf(cgroup_path, path_size, "%s/%s", path, SUBTREE_CONTROL);
cgroup_file = fopen(cgroup_path, "we");
if (!cgroup_file) {
perror("fopen");
goto error;
}
fprintf(cgroup_file, "+cpu");
if (fclose(cgroup_file)) {
perror("fclose");
goto error;
}
free(cgroup_path);
}
next:
dir[i] = del;
} while (dir[i]);
Expand Down Expand Up @@ -373,7 +435,35 @@ static int cgroup_attach_task(char *name)
FILE *tasks;
size_t size;

file = strcmp(name, "/") ? "/tasks" : "tasks";
if (ctrl.version == 1) {
file = strcmp(name, "/") ? "/tasks" : "tasks";
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@Werkov Werkov Oct 3, 2024

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I wonder it this special casing for root cgrp is worth it (here and other places).

-sprintf(path, "%s%s%s", ctrl.mount_point, name, file);
+sprintf(path, "%s%s/%s", ctrl.mount_point, name, file);

with possibly double // being resolved by open.

}

if (ctrl.version == 2) {
if (strcmp(name, "/")) {
size_t path_size = strlen(ctrl.mount_point) + strlen(name) + strlen(TYPE) + 3;
char* cgroup_path = malloc(path_size);
FILE* cgroup_file;

snprintf(cgroup_path, path_size, "%s/%s/%s", ctrl.mount_point, name, TYPE);
cgroup_file = fopen(cgroup_path, "we");
if (!cgroup_file) {
perror("open");
goto error;
}
if (fprintf(cgroup_file, "threaded") < 0) {
perror("fprintf");
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@Werkov Werkov Oct 3, 2024

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cgroup_file not closed here

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@Werkov Werkov Oct 3, 2024

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Also some better message may ease future debugging, like cgroup.type <- threaded failed.

goto error;
}
if (fclose(cgroup_file)) {
perror("fclose");
goto error;
}
free(cgroup_path);
}
file = strcmp(name, "/") ? "/cgroup.threads" : "cgroup.threads";
}

size = strlen(ctrl.mount_point) + strlen(name) + strlen(file) + 1;
path = malloc(size);
if (!path) {
Expand All @@ -393,9 +483,11 @@ static int cgroup_attach_task(char *name)
goto error;
}

if (fclose(tasks)) {
perror("fclose");
goto error;
if (ctrl.version == 1) {
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@Werkov Werkov Oct 3, 2024

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v2 file deserves to be closed here too, no?

if (fclose(tasks)) {
perror("fclose");
goto error;
}
}

ret = 0;
Expand Down