Merge tag 'driver-core-3.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git...

[karo-tx-linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0f3527d6184a1597fb81f00a878df15eeab0ecf8..2097684cf19474aee676513af39de14035c4fce7 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -255,12 +255,17 @@ int cgroup_lock_is_held(void)
 
 EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
 
+static int css_unbias_refcnt(int refcnt)
+{
+       return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS;
+}
+
 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
 static int css_refcnt(struct cgroup_subsys_state *css)
 {
        int v = atomic_read(&css->refcnt);
 
-       return v >= 0 ? v : v - CSS_DEACT_BIAS;
+       return css_unbias_refcnt(v);
 }
 
 /* convenient tests for these bits */
@@ -896,10 +901,13 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                mutex_unlock(&cgroup_mutex);
 
                /*
-                * Drop the active superblock reference that we took when we
-                * created the cgroup
+                * We want to drop the active superblock reference from the
+                * cgroup creation after all the dentry refs are gone -
+                * kill_sb gets mighty unhappy otherwise.  Mark
+                * dentry->d_fsdata with cgroup_diput() to tell
+                * cgroup_d_release() to call deactivate_super().
                 */
-               deactivate_super(cgrp->root->sb);
+               dentry->d_fsdata = cgroup_diput;
 
                /*
                 * if we're getting rid of the cgroup, refcount should ensure
@@ -925,6 +933,13 @@ static int cgroup_delete(const struct dentry *d)
        return 1;
 }
 
+static void cgroup_d_release(struct dentry *dentry)
+{
+       /* did cgroup_diput() tell me to deactivate super? */
+       if (dentry->d_fsdata == cgroup_diput)
+               deactivate_super(dentry->d_sb);
+}
+
 static void remove_dir(struct dentry *d)
 {
        struct dentry *parent = dget(d->d_parent);
@@ -1532,6 +1547,7 @@ static int cgroup_get_rootdir(struct super_block *sb)
        static const struct dentry_operations cgroup_dops = {
                .d_iput = cgroup_diput,
                .d_delete = cgroup_delete,
+               .d_release = cgroup_d_release,
        };
 
        struct inode *inode =
@@ -4971,10 +4987,12 @@ EXPORT_SYMBOL_GPL(__css_tryget);
 void __css_put(struct cgroup_subsys_state *css)
 {
        struct cgroup *cgrp = css->cgroup;
+       int v;
 
        rcu_read_lock();
-       atomic_dec(&css->refcnt);
-       switch (css_refcnt(css)) {
+       v = css_unbias_refcnt(atomic_dec_return(&css->refcnt));
+
+       switch (v) {
        case 1:
                if (notify_on_release(cgrp)) {
                        set_bit(CGRP_RELEASABLE, &cgrp->flags);