[lxc-devel] [lxc/master] cgfs: various fixes
brauner on Github
lxc-bot at linuxcontainers.org
Sun Oct 30 14:15:03 UTC 2016
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From 1a704014eeedf1c52135e520962fcff94fdf67c3 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at canonical.com>
Date: Sun, 30 Oct 2016 10:45:13 +0100
Subject: [PATCH 1/3] cgfs: add print_cgfs_init_debuginfo()
Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
---
src/lxc/cgroups/cgfs.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/src/lxc/cgroups/cgfs.c b/src/lxc/cgroups/cgfs.c
index 26cccad..c10253b 100644
--- a/src/lxc/cgroups/cgfs.c
+++ b/src/lxc/cgroups/cgfs.c
@@ -2270,6 +2270,33 @@ static bool init_cpuset_if_needed(struct cgroup_mount_point *mp,
do_init_cpuset_file(mp, path, "/cpuset.mems") );
}
+static void print_cgfs_init_debuginfo(struct cgfs_data *d)
+{
+ int i;
+
+ if (!getenv("LXC_DEBUG_CGFS"))
+ return;
+
+ DEBUG("Cgroup information:");
+ DEBUG(" container name: %s", d->name);
+ if (!d->meta || !d->meta->hierarchies) {
+ DEBUG(" No hierarchies found.");
+ return;
+ }
+ DEBUG(" Controllers:");
+ for (i = 0; i <= d->meta->maximum_hierarchy; i++) {
+ char **p;
+ struct cgroup_hierarchy *h = d->meta->hierarchies[i];
+ if (!h) {
+ DEBUG(" Empty hierarchy number %d.", i);
+ continue;
+ }
+ for (p = h->subsystems; p && *p; p++) {
+ DEBUG(" %2d: %s", i, *p);
+ }
+ }
+}
+
struct cgroup_ops *cgfs_ops_init(void)
{
return &cgfs_ops;
@@ -2295,6 +2322,9 @@ static void *cgfs_init(const char *name)
ERROR("cgroupfs failed to detect cgroup metadata");
goto err2;
}
+
+ print_cgfs_init_debuginfo(d);
+
return d;
err2:
From 82a2fe03a61febcc1b2300550a70ac698cb1fd11 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at canonical.com>
Date: Sun, 30 Oct 2016 13:42:37 +0100
Subject: [PATCH 2/3] cgfs: skip empty entries under /proc/self/cgroup
If cgroupv2 is enabled either alone or together with legacy hierarchies
/proc/self/cgroup can contain entries of the form:
0::/
These entries need to be skipped.
Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
---
src/lxc/cgroups/cgfs.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/src/lxc/cgroups/cgfs.c b/src/lxc/cgroups/cgfs.c
index c10253b..a30ad91 100644
--- a/src/lxc/cgroups/cgfs.c
+++ b/src/lxc/cgroups/cgfs.c
@@ -364,6 +364,14 @@ static bool find_cgroup_hierarchies(struct cgroup_meta_data *meta_data,
*colon2 = '\0';
colon2 = NULL;
+
+ /* With cgroupv2 /proc/self/cgroup can contain entries of the
+ * form: 0::/
+ * These entries need to be skipped.
+ */
+ if (!strcmp(colon1, ""))
+ continue;
+
hierarchy_number = strtoul(line, &colon2, 10);
if (!colon2 || *colon2)
continue;
@@ -1685,6 +1693,14 @@ lxc_cgroup_process_info_getx(const char *proc_pid_cgroup_str,
*colon2++ = '\0';
endptr = NULL;
+
+ /* With cgroupv2 /proc/self/cgroup can contain entries of the
+ * form: 0::/
+ * These entries need to be skipped.
+ */
+ if (!strcmp(colon1, ""))
+ continue;
+
hierarchy_number = strtoul(line, &endptr, 10);
if (!endptr || *endptr)
continue;
From e138cc68b3a3ba2fdb72d633bc2cfd004de15008 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at canonical.com>
Date: Sun, 30 Oct 2016 14:44:33 +0100
Subject: [PATCH 3/3] cgfs: start counter for cgroups hierarchies at 1
Somehow this implementation of a cgroupfs backend decided to use the hierarchy
numbers it detects in /proc/cgroups and /proc/self/cgroups as indices for
the hierarchy struct. Controller numbering usually starts at 1 but may start at
0 if:
a) the controller is not mounted on a cgroups v1 hierarchy;
b) the controller is bound to the cgroups v2 single unified hierarchy; or
c) the controller is disabled
To avoid having to rework our fallback backend significantly, we should
explicitly check for each controller if hierarchy[i] != NULL.
Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
---
src/lxc/cgroups/cgfs.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/src/lxc/cgroups/cgfs.c b/src/lxc/cgroups/cgfs.c
index a30ad91..8499200 100644
--- a/src/lxc/cgroups/cgfs.c
+++ b/src/lxc/cgroups/cgfs.c
@@ -512,7 +512,7 @@ static bool find_hierarchy_mountpts( struct cgroup_meta_data *meta_data, char **
goto out;
h = NULL;
- for (k = 1; k <= meta_data->maximum_hierarchy; k++) {
+ for (k = 0; k <= meta_data->maximum_hierarchy; k++) {
if (meta_data->hierarchies[k] &&
meta_data->hierarchies[k]->subsystems[0] &&
lxc_string_in_array(meta_data->hierarchies[k]->subsystems[0], (const char **)subsystems)) {
@@ -654,6 +654,8 @@ static struct cgroup_hierarchy *lxc_cgroup_find_hierarchy(struct cgroup_meta_dat
size_t i;
for (i = 0; i <= meta_data->maximum_hierarchy; i++) {
struct cgroup_hierarchy *h = meta_data->hierarchies[i];
+ if (!h)
+ continue;
if (h && lxc_string_in_array(subsystem, (const char **)h->subsystems))
return h;
}
@@ -892,6 +894,8 @@ static struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const c
/* find mount points we can use */
for (info_ptr = base_info; info_ptr; info_ptr = info_ptr->next) {
h = info_ptr->hierarchy;
+ if (!h)
+ continue;
mp = lxc_cgroup_find_mount_point(h, info_ptr->cgroup_path, true);
if (!mp) {
ERROR("Could not find writable mount point for cgroup hierarchy %d while trying to create cgroup.", h->index);
@@ -981,6 +985,9 @@ static struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const c
for (i = 0, info_ptr = base_info; info_ptr; info_ptr = info_ptr->next, i++) {
char *parts2[3];
+ if (!info_ptr->hierarchy)
+ continue;
+
if (lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems))
continue;
current_entire_path = NULL;
@@ -1079,6 +1086,8 @@ static struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const c
/* we're done, now update the paths */
for (i = 0, info_ptr = base_info; info_ptr; info_ptr = info_ptr->next, i++) {
+ if (!info_ptr->hierarchy)
+ continue;
/* ignore legacy 'ns' subsystem here, lxc_cgroup_create_legacy
* will take care of it
* Since we do a continue in above loop, new_cgroup_paths[i] is
@@ -1116,6 +1125,9 @@ static int lxc_cgroup_create_legacy(struct cgroup_process_info *base_info, const
int r;
for (info_ptr = base_info; info_ptr; info_ptr = info_ptr->next) {
+ if (!info_ptr->hierarchy)
+ continue;
+
if (!lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems))
continue;
/*
@@ -1200,6 +1212,9 @@ static int lxc_cgroupfs_enter(struct cgroup_process_info *info, pid_t pid, bool
snprintf(pid_buf, 32, "%lu", (unsigned long)pid);
for (info_ptr = info; info_ptr; info_ptr = info_ptr->next) {
+ if (!info_ptr->hierarchy)
+ continue;
+
char *cgroup_path = (enter_sub && info_ptr->cgroup_path_sub) ?
info_ptr->cgroup_path_sub :
info_ptr->cgroup_path;
@@ -1444,6 +1459,10 @@ static bool cgroupfs_mount_cgroup(void *hdata, const char *root, int type)
for (info = base_info; info; info = info->next) {
size_t subsystem_count, i;
struct cgroup_mount_point *mp = info->designated_mount_point;
+
+ if (!info->hierarchy)
+ continue;
+
if (!mountpoint_is_accessible(mp))
mp = lxc_cgroup_find_mount_point(info->hierarchy, info->cgroup_path, true);
@@ -1930,6 +1949,8 @@ find_info_for_subsystem(struct cgroup_process_info *info, const char *subsystem)
struct cgroup_process_info *info_ptr;
for (info_ptr = info; info_ptr; info_ptr = info_ptr->next) {
struct cgroup_hierarchy *h = info_ptr->hierarchy;
+ if (!h)
+ continue;
if (lxc_string_in_array(subsystem, (const char **)h->subsystems))
return info_ptr;
}
@@ -2426,7 +2447,7 @@ static bool cgfs_escape(void *hdata)
if (!md)
return false;
- for (i = 1; i <= md->maximum_hierarchy; i++) {
+ for (i = 0; i <= md->maximum_hierarchy; i++) {
struct cgroup_hierarchy *h = md->hierarchies[i];
struct cgroup_mount_point *mp;
char *tasks;
@@ -2636,6 +2657,9 @@ static bool cgfs_chown(void *hdata, struct lxc_conf *conf)
return false;
for (info_ptr = d->info; info_ptr; info_ptr = info_ptr->next) {
+ if (!info_ptr->hierarchy)
+ continue;
+
if (!info_ptr->designated_mount_point) {
info_ptr->designated_mount_point = lxc_cgroup_find_mount_point(info_ptr->hierarchy, info_ptr->cgroup_path, true);
if (!info_ptr->designated_mount_point) {
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