Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cascardo/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4406615..85bc9be 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -64,6 +64,9 @@
 #include <linux/file.h>
 #include <net/sock.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/cgroup.h>
+
 /*
  * pidlists linger the following amount before being destroyed.  The goal
  * is avoiding frequent destruction in the middle of consecutive read calls
@@ -1176,6 +1179,8 @@ static void cgroup_destroy_root(struct cgroup_root *root)
        struct cgroup *cgrp = &root->cgrp;
        struct cgrp_cset_link *link, *tmp_link;
 
+       trace_cgroup_destroy_root(root);
+
        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
 
        BUG_ON(atomic_read(&root->nr_cgrps));
@@ -1874,6 +1879,9 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
                strcpy(root->release_agent_path, opts.release_agent);
                spin_unlock(&release_agent_path_lock);
        }
+
+       trace_cgroup_remount(root);
+
  out_unlock:
        kfree(opts.release_agent);
        kfree(opts.name);
@@ -2031,6 +2039,8 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
        if (ret)
                goto destroy_root;
 
+       trace_cgroup_setup_root(root);
+
        /*
         * There must be no failure case after here, since rebinding takes
         * care of subsystems' refcounts, which are explicitly dropped in
@@ -2315,22 +2325,18 @@ static struct file_system_type cgroup2_fs_type = {
        .fs_flags = FS_USERNS_MOUNT,
 };
 
-static char *cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
-                                  struct cgroup_namespace *ns)
+static int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+                                struct cgroup_namespace *ns)
 {
        struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
-       int ret;
 
-       ret = kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
-       if (ret < 0 || ret >= buflen)
-               return NULL;
-       return buf;
+       return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
 }
 
-char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
-                    struct cgroup_namespace *ns)
+int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
+                  struct cgroup_namespace *ns)
 {
-       char *ret;
+       int ret;
 
        mutex_lock(&cgroup_mutex);
        spin_lock_irq(&css_set_lock);
@@ -2357,12 +2363,12 @@ EXPORT_SYMBOL_GPL(cgroup_path_ns);
  *
  * Return value is the same as kernfs_path().
  */
-char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
 {
        struct cgroup_root *root;
        struct cgroup *cgrp;
        int hierarchy_id = 1;
-       char *path = NULL;
+       int ret;
 
        mutex_lock(&cgroup_mutex);
        spin_lock_irq(&css_set_lock);
@@ -2371,16 +2377,15 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
 
        if (root) {
                cgrp = task_cgroup_from_root(task, root);
-               path = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
+               ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
        } else {
                /* if no hierarchy exists, everyone is in "/" */
-               if (strlcpy(buf, "/", buflen) < buflen)
-                       path = buf;
+               ret = strlcpy(buf, "/", buflen);
        }
 
        spin_unlock_irq(&css_set_lock);
        mutex_unlock(&cgroup_mutex);
-       return path;
+       return ret;
 }
 EXPORT_SYMBOL_GPL(task_cgroup_path);
 
@@ -2830,6 +2835,10 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp,
                ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root);
 
        cgroup_migrate_finish(&preloaded_csets);
+
+       if (!ret)
+               trace_cgroup_attach_task(dst_cgrp, leader, threadgroup);
+
        return ret;
 }
 
@@ -3611,6 +3620,8 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
        mutex_lock(&cgroup_mutex);
 
        ret = kernfs_rename(kn, new_parent, new_name_str);
+       if (!ret)
+               trace_cgroup_rename(cgrp);
 
        mutex_unlock(&cgroup_mutex);
 
@@ -4381,6 +4392,8 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
 
                if (task) {
                        ret = cgroup_migrate(task, false, to->root);
+                       if (!ret)
+                               trace_cgroup_transfer_tasks(to, task, false);
                        put_task_struct(task);
                }
        } while (task && !ret);
@@ -5046,6 +5059,8 @@ static void css_release_work_fn(struct work_struct *work)
                        ss->css_released(css);
        } else {
                /* cgroup release path */
+               trace_cgroup_release(cgrp);
+
                cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
                cgrp->id = -1;
 
@@ -5332,6 +5347,8 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
        if (ret)
                goto out_destroy;
 
+       trace_cgroup_mkdir(cgrp);
+
        /* let's create and online css's */
        kernfs_activate(kn);
 
@@ -5507,6 +5524,9 @@ static int cgroup_rmdir(struct kernfs_node *kn)
 
        ret = cgroup_destroy_locked(cgrp);
 
+       if (!ret)
+               trace_cgroup_rmdir(cgrp);
+
        cgroup_kn_unlock(kn);
        return ret;
 }
@@ -5743,7 +5763,7 @@ core_initcall(cgroup_wq_init);
 int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
                     struct pid *pid, struct task_struct *tsk)
 {
-       char *buf, *path;
+       char *buf;
        int retval;
        struct cgroup_root *root;
 
@@ -5786,18 +5806,18 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
                 * " (deleted)" is appended to the cgroup path.
                 */
                if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
-                       path = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
+                       retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
                                                current->nsproxy->cgroup_ns);
-                       if (!path) {
+                       if (retval >= PATH_MAX)
                                retval = -ENAMETOOLONG;
+                       if (retval < 0)
                                goto out_unlock;
-                       }
+
+                       seq_puts(m, buf);
                } else {
-                       path = "/";
+                       seq_puts(m, "/");
                }
 
-               seq_puts(m, path);
-
                if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
                        seq_puts(m, " (deleted)\n");
                else
@@ -6062,8 +6082,9 @@ static void cgroup_release_agent(struct work_struct *work)
 {
        struct cgroup *cgrp =
                container_of(work, struct cgroup, release_agent_work);
-       char *pathbuf = NULL, *agentbuf = NULL, *path;
+       char *pathbuf = NULL, *agentbuf = NULL;
        char *argv[3], *envp[3];
+       int ret;
 
        mutex_lock(&cgroup_mutex);
 
@@ -6073,13 +6094,13 @@ static void cgroup_release_agent(struct work_struct *work)
                goto out;
 
        spin_lock_irq(&css_set_lock);
-       path = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+       ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
        spin_unlock_irq(&css_set_lock);
-       if (!path)
+       if (ret < 0 || ret >= PATH_MAX)
                goto out;
 
        argv[0] = agentbuf;
-       argv[1] = path;
+       argv[1] = pathbuf;
        argv[2] = NULL;
 
        /* minimal command environment */