Merge branch 'p-ti-linux-3.8.y' into p-ti-android-3.8.y

[android-sdk/kernel-video.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4855892798fdfd6aeee695a4fc1d2a70b96662eb..f28c151d30cabe4d32855d1393cafc9f52c12f3c 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -162,6 +162,9 @@ struct cfent {
        struct list_head                node;
        struct dentry                   *dentry;
        struct cftype                   *type;
+
+       /* file xattrs */
+       struct simple_xattrs            xattrs;
 };
 
 /*
@@ -426,12 +429,20 @@ static void __put_css_set(struct css_set *cg, int taskexit)
                struct cgroup *cgrp = link->cgrp;
                list_del(&link->cg_link_list);
                list_del(&link->cgrp_link_list);
+
+               /*
+                * We may not be holding cgroup_mutex, and if cgrp->count is
+                * dropped to 0 the cgroup can be destroyed at any time, hence
+                * rcu_read_lock is used to keep it alive.
+                */
+               rcu_read_lock();
                if (atomic_dec_and_test(&cgrp->count) &&
                    notify_on_release(cgrp)) {
                        if (taskexit)
                                set_bit(CGRP_RELEASABLE, &cgrp->flags);
                        check_for_release(cgrp);
                }
+               rcu_read_unlock();
 
                kfree(link);
        }
@@ -900,13 +911,12 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
        } else {
                struct cfent *cfe = __d_cfe(dentry);
                struct cgroup *cgrp = dentry->d_parent->d_fsdata;
-               struct cftype *cft = cfe->type;
 
                WARN_ONCE(!list_empty(&cfe->node) &&
                          cgrp != &cgrp->root->top_cgroup,
                          "cfe still linked for %s\n", cfe->type->name);
+               simple_xattrs_free(&cfe->xattrs);
                kfree(cfe);
-               simple_xattrs_free(&cft->xattrs);
        }
        iput(inode);
 }
@@ -2058,7 +2068,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
        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);
+       retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
        if (retval)
                goto out_free_group_list;
 
@@ -2176,6 +2186,24 @@ out_free_group_list:
        return retval;
 }
 
+static int cgroup_allow_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
+{
+       struct cgroup_subsys *ss;
+       int ret;
+
+       for_each_subsys(cgrp->root, ss) {
+               if (ss->allow_attach) {
+                       ret = ss->allow_attach(cgrp, tset);
+                       if (ret)
+                               return ret;
+               } else {
+                       return -EACCES;
+               }
+       }
+
+       return 0;
+}
+
 /*
  * Find the task_struct of the task to attach by vpid and pass it along to the
  * function to attach either it or all tasks in its threadgroup. Will lock
@@ -2207,9 +2235,18 @@ retry_find_task:
                if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
                    !uid_eq(cred->euid, tcred->uid) &&
                    !uid_eq(cred->euid, tcred->suid)) {
-                       rcu_read_unlock();
-                       ret = -EACCES;
-                       goto out_unlock_cgroup;
+                       /*
+                        * if the default permission check fails, give each
+                        * cgroup a chance to extend the permission check
+                        */
+                       struct cgroup_taskset tset = { };
+                       tset.single.task = tsk;
+                       tset.single.cgrp = cgrp;
+                       ret = cgroup_allow_attach(cgrp, &tset);
+                       if (ret) {
+                               rcu_read_unlock();
+                               goto out_unlock_cgroup;
+                       }
                }
        } else
                tsk = current;
@@ -2545,7 +2582,7 @@ static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
        if (S_ISDIR(dentry->d_inode->i_mode))
                return &__d_cgrp(dentry)->xattrs;
        else
-               return &__d_cft(dentry)->xattrs;
+               return &__d_cfe(dentry)->xattrs;
 }
 
 static inline int xattr_enabled(struct dentry *dentry)
@@ -2721,8 +2758,6 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
        umode_t mode;
        char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
 
-       simple_xattrs_init(&cft->xattrs);
-
        if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
                strcpy(name, subsys->name);
                strcat(name, ".");
@@ -2747,6 +2782,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
                cfe->type = (void *)cft;
                cfe->dentry = dentry;
                dentry->d_fsdata = cfe;
+               simple_xattrs_init(&cfe->xattrs);
                list_add_tail(&cfe->node, &parent->files);
                cfe = NULL;
        }