Merge remote-tracking branches 'asoc/fix/atmel', 'asoc/fix/fsl', 'asoc/fix/tegra...

[linux-drm-fsl-dcu.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4c62513fe19fc8c4b938aeb8b3acb5158da2f976..8b729c278b649c7c016786f6dac9886290ce794f 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -89,6 +89,14 @@ static DEFINE_MUTEX(cgroup_mutex);
 
 static DEFINE_MUTEX(cgroup_root_mutex);
 
+/*
+ * cgroup destruction makes heavy use of work items and there can be a lot
+ * of concurrent destructions.  Use a separate workqueue so that cgroup
+ * destruction work items don't end up filling up max_active of system_wq
+ * which may lead to deadlock.
+ */
+static struct workqueue_struct *cgroup_destroy_wq;
+
 /*
  * Generate an array of cgroup subsystem pointers. At boot time, this is
  * populated with the built in subsystems, and modular subsystems are
@@ -191,6 +199,7 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp);
 static int cgroup_destroy_locked(struct cgroup *cgrp);
 static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
                              bool is_add);
+static int cgroup_file_release(struct inode *inode, struct file *file);
 
 /**
  * cgroup_css - obtain a cgroup's css for the specified subsystem
@@ -871,7 +880,7 @@ static void cgroup_free_rcu(struct rcu_head *head)
        struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);
 
        INIT_WORK(&cgrp->destroy_work, cgroup_free_fn);
-       schedule_work(&cgrp->destroy_work);
+       queue_work(cgroup_destroy_wq, &cgrp->destroy_work);
 }
 
 static void cgroup_diput(struct dentry *dentry, struct inode *inode)
@@ -2421,7 +2430,7 @@ static const struct file_operations cgroup_seqfile_operations = {
        .read = seq_read,
        .write = cgroup_file_write,
        .llseek = seq_lseek,
-       .release = single_release,
+       .release = cgroup_file_release,
 };
 
 static int cgroup_file_open(struct inode *inode, struct file *file)
@@ -2482,6 +2491,8 @@ static int cgroup_file_release(struct inode *inode, struct file *file)
                ret = cft->release(inode, file);
        if (css->ss)
                css_put(css);
+       if (file->f_op == &cgroup_seqfile_operations)
+               single_release(inode, file);
        return ret;
 }
 
@@ -4249,7 +4260,7 @@ static void css_free_rcu_fn(struct rcu_head *rcu_head)
         * css_put().  dput() requires process context which we don't have.
         */
        INIT_WORK(&css->destroy_work, css_free_work_fn);
-       schedule_work(&css->destroy_work);
+       queue_work(cgroup_destroy_wq, &css->destroy_work);
 }
 
 static void css_release(struct percpu_ref *ref)
@@ -4539,7 +4550,7 @@ static void css_killed_ref_fn(struct percpu_ref *ref)
                container_of(ref, struct cgroup_subsys_state, refcnt);
 
        INIT_WORK(&css->destroy_work, css_killed_work_fn);
-       schedule_work(&css->destroy_work);
+       queue_work(cgroup_destroy_wq, &css->destroy_work);
 }
 
 /**
@@ -5063,6 +5074,22 @@ out:
        return err;
 }
 
+static int __init cgroup_wq_init(void)
+{
+       /*
+        * There isn't much point in executing destruction path in
+        * parallel.  Good chunk is serialized with cgroup_mutex anyway.
+        * Use 1 for @max_active.
+        *
+        * We would prefer to do this in cgroup_init() above, but that
+        * is called before init_workqueues(): so leave this until after.
+        */
+       cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
+       BUG_ON(!cgroup_destroy_wq);
+       return 0;
+}
+core_initcall(cgroup_wq_init);
+
 /*
  * proc_cgroup_show()
  *  - Print task's cgroup paths into seq_file, one line for each hierarchy