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

[~andy/linux] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e2f46ba37f7243c4278de77a8c8536ddc4c0aad5..105f273b6f86a74984d2b62b7d3ba19f95369a78 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -886,7 +886,9 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                 * per-subsystem and moved to css->id so that lookups are
                 * successful until the target css is released.
                 */
+               mutex_lock(&cgroup_mutex);
                idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
+               mutex_unlock(&cgroup_mutex);
                cgrp->id = -1;
 
                call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
@@ -1566,10 +1568,10 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
                mutex_lock(&cgroup_mutex);
                mutex_lock(&cgroup_root_mutex);
 
-               root_cgrp->id = idr_alloc(&root->cgroup_idr, root_cgrp,
-                                          0, 1, GFP_KERNEL);
-               if (root_cgrp->id < 0)
+               ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
+               if (ret < 0)
                        goto unlock_drop;
+               root_cgrp->id = ret;
 
                /* Check for name clashes with existing mounts */
                ret = -EBUSY;
@@ -2763,10 +2765,7 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
         */
        update_before = cgroup_serial_nr_next;
 
-       mutex_unlock(&cgroup_mutex);
-
        /* add/rm files for all cgroups created before */
-       rcu_read_lock();
        css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
                struct cgroup *cgrp = css->cgroup;
 
@@ -2775,23 +2774,19 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
 
                inode = cgrp->dentry->d_inode;
                dget(cgrp->dentry);
-               rcu_read_unlock();
-
                dput(prev);
                prev = cgrp->dentry;
 
+               mutex_unlock(&cgroup_mutex);
                mutex_lock(&inode->i_mutex);
                mutex_lock(&cgroup_mutex);
                if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
                        ret = cgroup_addrm_files(cgrp, cfts, is_add);
-               mutex_unlock(&cgroup_mutex);
                mutex_unlock(&inode->i_mutex);
-
-               rcu_read_lock();
                if (ret)
                        break;
        }
-       rcu_read_unlock();
+       mutex_unlock(&cgroup_mutex);
        dput(prev);
        deactivate_super(sb);
        return ret;
@@ -2910,9 +2905,14 @@ static void cgroup_enable_task_cg_lists(void)
                 * We should check if the process is exiting, otherwise
                 * it will race with cgroup_exit() in that the list
                 * entry won't be deleted though the process has exited.
+                * Do it while holding siglock so that we don't end up
+                * racing against cgroup_exit().
                 */
+               spin_lock_irq(&p->sighand->siglock);
                if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
                        list_add(&p->cg_list, &task_css_set(p)->tasks);
+               spin_unlock_irq(&p->sighand->siglock);
+
                task_unlock(p);
        } while_each_thread(g, p);
        read_unlock(&tasklist_lock);
@@ -4158,7 +4158,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
        struct cgroup *cgrp;
        struct cgroup_name *name;
        struct cgroupfs_root *root = parent->root;
-       int ssid, err = 0;
+       int ssid, err;
        struct cgroup_subsys *ss;
        struct super_block *sb = root->sb;
 
@@ -4168,18 +4168,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                return -ENOMEM;
 
        name = cgroup_alloc_name(dentry);
-       if (!name)
+       if (!name) {
+               err = -ENOMEM;
                goto err_free_cgrp;
+       }
        rcu_assign_pointer(cgrp->name, name);
 
-       /*
-        * Temporarily set the pointer to NULL, so idr_find() won't return
-        * a half-baked cgroup.
-        */
-       cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
-       if (cgrp->id < 0)
-               goto err_free_name;
-
        /*
         * Only live parents can have children.  Note that the liveliness
         * check isn't strictly necessary because cgroup_mkdir() and
@@ -4189,7 +4183,17 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
         */
        if (!cgroup_lock_live_group(parent)) {
                err = -ENODEV;
-               goto err_free_id;
+               goto err_free_name;
+       }
+
+       /*
+        * Temporarily set the pointer to NULL, so idr_find() won't return
+        * a half-baked cgroup.
+        */
+       cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
+       if (cgrp->id < 0) {
+               err = -ENOMEM;
+               goto err_unlock;
        }
 
        /* Grab a reference on the superblock so the hierarchy doesn't
@@ -4221,7 +4225,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
         */
        err = cgroup_create_file(dentry, S_IFDIR | mode, sb);
        if (err < 0)
-               goto err_unlock;
+               goto err_free_id;
        lockdep_assert_held(&dentry->d_inode->i_mutex);
 
        cgrp->serial_nr = cgroup_serial_nr_next++;
@@ -4257,12 +4261,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
        return 0;
 
-err_unlock:
-       mutex_unlock(&cgroup_mutex);
-       /* Release the reference count that we took on the superblock */
-       deactivate_super(sb);
 err_free_id:
        idr_remove(&root->cgroup_idr, cgrp->id);
+       /* Release the reference count that we took on the superblock */
+       deactivate_super(sb);
+err_unlock:
+       mutex_unlock(&cgroup_mutex);
 err_free_name:
        kfree(rcu_dereference_raw(cgrp->name));
 err_free_cgrp: