cgroups: improve cgfsng debugging

In a lot of cases we need a list of the writeable cgroup controllers detected
by the cgfsng driver.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 5ad874e82785e7dda013372b89477ea5ce46028a..ebd548b9f8e7d7cb50558c7d083480cfeaec396c 100644 (file)
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -101,6 +101,12 @@ struct hierarchy **hierarchies;
  */
 char *cgroup_use;
 
+/*
+ * @lxc_cgfsng_debug - whether to print debug info to stdout for the cgfsng
+ * driver
+ */
+static bool lxc_cgfsng_debug;
+
 static void free_string_list(char **clist)
 {
        if (clist) {
@@ -990,41 +996,40 @@ static void trim(char *s)
                s[--len] = '\0';
 }
 
-static void print_init_debuginfo(struct cgfsng_handler_data *d)
+static void lxc_cgfsng_print_handler_data(const struct cgfsng_handler_data *d)
+{
+       printf("Cgroup information:\n");
+       printf("  container name: %s\n", d->name ? d->name : "(null)");
+       printf("  lxc.cgroup.use: %s\n", cgroup_use ? cgroup_use : "(null)");
+       printf("  lxc.cgroup.pattern: %s\n", d->cgroup_pattern ? d->cgroup_pattern : "(null)");
+       printf("  cgroup: %s\n", d->container_cgroup ? d->container_cgroup : "(null)");
+}
+
+static void lxc_cgfsng_print_hierarchies()
 {
        struct hierarchy **it;
        int i;
 
-       if (!getenv("LXC_DEBUG_CGFSNG"))
-               return;
-
-       DEBUG("Cgroup information:");
-       DEBUG("  container name: %s", d->name ? d->name : "(null)");
-       DEBUG("  lxc.cgroup.use: %s", cgroup_use ? cgroup_use : "(null)");
-       DEBUG("  lxc.cgroup.pattern: %s", d->cgroup_pattern ? d->cgroup_pattern : "(null)");
-       DEBUG("  cgroup: %s", d->container_cgroup ? d->container_cgroup : "(null)");
        if (!hierarchies) {
-               DEBUG("  No hierarchies found.");
+               printf("  No hierarchies found.");
                return;
        }
-       DEBUG("  Hierarchies:");
+       printf("  Hierarchies:\n");
        for (i = 0, it = hierarchies; it && *it; it++, i++) {
                char **cit;
                int j;
-               DEBUG("  %d: base_cgroup %s", i, (*it)->base_cgroup ? (*it)->base_cgroup : "(null)");
-               DEBUG("      mountpoint %s", (*it)->mountpoint ? (*it)->mountpoint : "(null)");
-               DEBUG("      controllers:");
+               printf("  %d: base_cgroup %s\n", i, (*it)->base_cgroup ? (*it)->base_cgroup : "(null)");
+               printf("      mountpoint %s\n", (*it)->mountpoint ? (*it)->mountpoint : "(null)");
+               printf("      controllers:\n");
                for (j = 0, cit = (*it)->controllers; cit && *cit; cit++, j++)
-                       DEBUG("      %d: %s", j, *cit);
+                       printf("      %d: %s\n", j, *cit);
        }
 }
 
-static void print_basecg_debuginfo(char *basecginfo, char **klist, char **nlist)
+static void lxc_cgfsng_print_basecg_debuginfo(char *basecginfo, char **klist, char **nlist)
 {
        int k;
        char **it;
-       if (!getenv("LXC_DEBUG_CGFSNG"))
-               return;
 
        printf("basecginfo is:\n");
        printf("%s\n", basecginfo);
@@ -1035,6 +1040,12 @@ static void print_basecg_debuginfo(char *basecginfo, char **klist, char **nlist)
                printf("named subsystem %d: %s\n", k, *it);
 }
 
+static void lxc_cgfsng_print_debuginfo(const struct cgfsng_handler_data *d)
+{
+       lxc_cgfsng_print_handler_data(d);
+       lxc_cgfsng_print_hierarchies();
+}
+
 /*
  * At startup, parse_hierarchies finds all the info we need about
  * cgroup mountpoints and current cgroups, and stores it in @d.
@@ -1064,7 +1075,8 @@ static bool parse_hierarchies(void)
 
        get_existing_subsystems(&klist, &nlist);
 
-       print_basecg_debuginfo(basecginfo, klist, nlist);
+       if (lxc_cgfsng_debug)
+               lxc_cgfsng_print_basecg_debuginfo(basecginfo, klist, nlist);
 
        /* we support simple cgroup mounts and lxcfs mounts */
        while (getline(&line, &len, f) != -1) {
@@ -1116,6 +1128,11 @@ static bool parse_hierarchies(void)
        fclose(f);
        free(line);
 
+       if (lxc_cgfsng_debug) {
+               printf("writeable subsystems:\n");
+               lxc_cgfsng_print_hierarchies();
+       }
+
        /* verify that all controllers in cgroup.use and all crucial
         * controllers are accounted for
         */
@@ -1156,7 +1173,8 @@ static void *cgfsng_init(const char *name)
        }
        d->cgroup_pattern = must_copy_string(cgroup_pattern);
 
-       print_init_debuginfo(d);
+       if (lxc_cgfsng_debug)
+               lxc_cgfsng_print_debuginfo(d);
 
        return d;
 
@@ -1294,8 +1312,12 @@ static void cgfsng_destroy(void *hdata, struct lxc_conf *conf)
 
 struct cgroup_ops *cgfsng_ops_init(void)
 {
+       if (getenv("LXC_DEBUG_CGFSNG"))
+               lxc_cgfsng_debug = true;
+
        if (!collect_hierarchy_info())
                return NULL;
+
        return &cgfsng_ops;
 }