rcu: Make lockdep_rcu_dereference() message less alarmist

[safe/jmp/linux-2.6] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d2b8859..4fd90e1 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -23,6 +23,7 @@
  */
 
 #include <linux/cgroup.h>
+#include <linux/module.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
@@ -166,6 +167,20 @@ static DEFINE_SPINLOCK(hierarchy_id_lock);
  */
 static int need_forkexit_callback __read_mostly;
 
+#ifdef CONFIG_PROVE_LOCKING
+int cgroup_lock_is_held(void)
+{
+       return lockdep_is_held(&cgroup_mutex);
+}
+#else /* #ifdef CONFIG_PROVE_LOCKING */
+int cgroup_lock_is_held(void)
+{
+       return mutex_is_locked(&cgroup_mutex);
+}
+#endif /* #else #ifdef CONFIG_PROVE_LOCKING */
+
+EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
+
 /* convenient tests for these bits */
 inline int cgroup_is_removed(const struct cgroup *cgrp)
 {
@@ -1710,14 +1725,13 @@ static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
                return -EFAULT;
 
        buffer[nbytes] = 0;     /* nul-terminate */
-       strstrip(buffer);
        if (cft->write_u64) {
-               u64 val = simple_strtoull(buffer, &end, 0);
+               u64 val = simple_strtoull(strstrip(buffer), &end, 0);
                if (*end)
                        return -EINVAL;
                retval = cft->write_u64(cgrp, cft, val);
        } else {
-               s64 val = simple_strtoll(buffer, &end, 0);
+               s64 val = simple_strtoll(strstrip(buffer), &end, 0);
                if (*end)
                        return -EINVAL;
                retval = cft->write_s64(cgrp, cft, val);
@@ -1753,8 +1767,7 @@ static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
        }
 
        buffer[nbytes] = 0;     /* nul-terminate */
-       strstrip(buffer);
-       retval = cft->write_string(cgrp, cft, buffer);
+       retval = cft->write_string(cgrp, cft, strstrip(buffer));
        if (!retval)
                retval = nbytes;
 out:
@@ -2470,7 +2483,6 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
                        /* make sure l doesn't vanish out from under us */
                        down_write(&l->mutex);
                        mutex_unlock(&cgrp->pidlist_mutex);
-                       l->use_count++;
                        return l;
                }
        }
@@ -2939,14 +2951,17 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
        for_each_subsys(root, ss) {
                struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+
                if (IS_ERR(css)) {
                        err = PTR_ERR(css);
                        goto err_destroy;
                }
                init_cgroup_css(css, ss, cgrp);
-               if (ss->use_id)
-                       if (alloc_css_id(ss, parent, cgrp))
+               if (ss->use_id) {
+                       err = alloc_css_id(ss, parent, cgrp);
+                       if (err)
                                goto err_destroy;
+               }
                /* At error, ->destroy() callback has to free assigned ID. */
        }
 
@@ -3708,8 +3723,10 @@ static void check_for_release(struct cgroup *cgrp)
 void __css_put(struct cgroup_subsys_state *css)
 {
        struct cgroup *cgrp = css->cgroup;
+       int val;
        rcu_read_lock();
-       if (atomic_dec_return(&css->refcnt) == 1) {
+       val = atomic_dec_return(&css->refcnt);
+       if (val == 1) {
                if (notify_on_release(cgrp)) {
                        set_bit(CGRP_RELEASABLE, &cgrp->flags);
                        check_for_release(cgrp);
@@ -3717,6 +3734,7 @@ void __css_put(struct cgroup_subsys_state *css)
                cgroup_wakeup_rmdir_waiter(cgrp);
        }
        rcu_read_unlock();
+       WARN_ON_ONCE(val < 1);
 }
 
 /*