#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
#include <linux/eventfd.h>
#include <linux/poll.h>
+#include <linux/flex_array.h> /* used in cgroup_attach_proc */
#include <asm/atomic.h>
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
struct task_struct *tsk;
- struct task_struct **group;
+ struct flex_array *group;
/*
* we need to make sure we have css_sets for all the tasks we're
* going to move -before- we actually start moving them, so that in
* and if threads exit, this will just be an over-estimate.
*/
group_size = get_nr_threads(leader);
- group = kmalloc(group_size * sizeof(*group), GFP_KERNEL);
+ /* flex_array supports very large thread-groups better than kmalloc. */
+ group = flex_array_alloc(sizeof(struct task_struct *), group_size,
+ GFP_KERNEL);
if (!group)
return -ENOMEM;
+ /* pre-allocate to guarantee space while iterating in rcu read-side. */
+ retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL);
+ if (retval)
+ goto out_free_group_list;
/* prevent changes to the threadgroup list while we take a snapshot. */
rcu_read_lock();
/* as per above, nr_threads may decrease, but not increase. */
BUG_ON(i >= group_size);
get_task_struct(tsk);
- group[i] = tsk;
+ /*
+ * saying GFP_ATOMIC has no effect here because we did prealloc
+ * earlier, but it's good form to communicate our expectations.
+ */
+ retval = flex_array_put_ptr(group, i, tsk, GFP_ATOMIC);
+ BUG_ON(retval != 0);
i++;
} while_each_thread(leader, tsk);
/* remember the number of threads in the array for later. */
if (ss->can_attach_task) {
/* run on each task in the threadgroup. */
for (i = 0; i < group_size; i++) {
- retval = ss->can_attach_task(cgrp, group[i]);
+ tsk = flex_array_get_ptr(group, i);
+ retval = ss->can_attach_task(cgrp, tsk);
if (retval) {
failed_ss = ss;
cancel_failed_ss = true;
*/
INIT_LIST_HEAD(&newcg_list);
for (i = 0; i < group_size; i++) {
- tsk = group[i];
+ tsk = flex_array_get_ptr(group, i);
/* nothing to do if this task is already in the cgroup */
oldcgrp = task_cgroup_from_root(tsk, root);
if (cgrp == oldcgrp)
ss->pre_attach(cgrp);
}
for (i = 0; i < group_size; i++) {
- tsk = group[i];
+ tsk = flex_array_get_ptr(group, i);
/* leave current thread as it is if it's already there */
oldcgrp = task_cgroup_from_root(tsk, root);
if (cgrp == oldcgrp)
}
}
/* clean up the array of referenced threads in the group. */
- for (i = 0; i < group_size; i++)
- put_task_struct(group[i]);
+ for (i = 0; i < group_size; i++) {
+ tsk = flex_array_get_ptr(group, i);
+ put_task_struct(tsk);
+ }
out_free_group_list:
- kfree(group);
+ flex_array_free(group);
return retval;
}
put_css_set_taskexit(cg);
}
-/**
- * cgroup_clone - clone the cgroup the given subsystem is attached to
- * @tsk: the task to be moved
- * @subsys: the given subsystem
- * @nodename: the name for the new cgroup
- *
- * Duplicate the current cgroup in the hierarchy that the given
- * subsystem is attached to, and move this task into the new
- * child.
- */
-int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
- char *nodename)
-{
- struct dentry *dentry;
- int ret = 0;
- struct cgroup *parent, *child;
- struct inode *inode;
- struct css_set *cg;
- struct cgroupfs_root *root;
- struct cgroup_subsys *ss;
-
- /* We shouldn't be called by an unregistered subsystem */
- BUG_ON(!subsys->active);
-
- /* First figure out what hierarchy and cgroup we're dealing
- * with, and pin them so we can drop cgroup_mutex */
- mutex_lock(&cgroup_mutex);
- again:
- root = subsys->root;
- if (root == &rootnode) {
- mutex_unlock(&cgroup_mutex);
- return 0;
- }
-
- /* Pin the hierarchy */
- if (!atomic_inc_not_zero(&root->sb->s_active)) {
- /* We race with the final deactivate_super() */
- mutex_unlock(&cgroup_mutex);
- return 0;
- }
-
- /* Keep the cgroup alive */
- task_lock(tsk);
- parent = task_cgroup(tsk, subsys->subsys_id);
- cg = tsk->cgroups;
- get_css_set(cg);
- task_unlock(tsk);
-
- mutex_unlock(&cgroup_mutex);
-
- /* Now do the VFS work to create a cgroup */
- inode = parent->dentry->d_inode;
-
- /* Hold the parent directory mutex across this operation to
- * stop anyone else deleting the new cgroup */
- mutex_lock(&inode->i_mutex);
- dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
- if (IS_ERR(dentry)) {
- printk(KERN_INFO
- "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
- PTR_ERR(dentry));
- ret = PTR_ERR(dentry);
- goto out_release;
- }
-
- /* Create the cgroup directory, which also creates the cgroup */
- ret = vfs_mkdir(inode, dentry, 0755);
- child = __d_cgrp(dentry);
- dput(dentry);
- if (ret) {
- printk(KERN_INFO
- "Failed to create cgroup %s: %d\n", nodename,
- ret);
- goto out_release;
- }
-
- /* The cgroup now exists. Retake cgroup_mutex and check
- * that we're still in the same state that we thought we
- * were. */
- mutex_lock(&cgroup_mutex);
- if ((root != subsys->root) ||
- (parent != task_cgroup(tsk, subsys->subsys_id))) {
- /* Aargh, we raced ... */
- mutex_unlock(&inode->i_mutex);
- put_css_set(cg);
-
- deactivate_super(root->sb);
- /* The cgroup is still accessible in the VFS, but
- * we're not going to try to rmdir() it at this
- * point. */
- printk(KERN_INFO
- "Race in cgroup_clone() - leaking cgroup %s\n",
- nodename);
- goto again;
- }
-
- /* do any required auto-setup */
- for_each_subsys(root, ss) {
- if (ss->post_clone)
- ss->post_clone(ss, child);
- }
-
- /* All seems fine. Finish by moving the task into the new cgroup */
- ret = cgroup_attach_task(child, tsk);
- mutex_unlock(&cgroup_mutex);
-
- out_release:
- mutex_unlock(&inode->i_mutex);
-
- mutex_lock(&cgroup_mutex);
- put_css_set(cg);
- mutex_unlock(&cgroup_mutex);
- deactivate_super(root->sb);
- return ret;
-}
-
/**
* cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
* @cgrp: the cgroup in question
projects / mv-sheeva.git / blobdiff