diff options
author | Tejun Heo <tj@kernel.org> | 2013-06-21 15:52:33 -0700 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2013-06-26 10:48:48 -0700 |
commit | a4ea1cc90604df08d471ae84eb9627319d10c844 (patch) | |
tree | 73e12ef6845c5cf5bac0b8a2e4e6c4dd03af0a1b /kernel/cgroup.c | |
parent | a8ad805cfde00be8fe3b3dae8890996dbeb91e2c (diff) | |
download | op-kernel-dev-a4ea1cc90604df08d471ae84eb9627319d10c844.zip op-kernel-dev-a4ea1cc90604df08d471ae84eb9627319d10c844.tar.gz |
cgroup: always use RCU accessors for protected accesses
kernel/cgroup.c still has places where a RCU pointer is set and
accessed directly without going through RCU_INIT_POINTER() or
rcu_dereference_protected(). They're all properly protected accesses
so nothing is broken but it leads to spurious sparse RCU address space
warnings.
Substitute direct accesses with RCU_INIT_POINTER() and
rcu_dereference_protected(). Note that %true is specified as the
extra condition for all derference updates. This isn't ideal as all
it does is suppressing warning without actually policing
synchronization rules; however, most are scheduled to be removed
pretty soon along with css_id itself, so no reason to be more
elaborate.
Combined with the previous changes, this removes all RCU related
sparse warnings from cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by; Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r-- | kernel/cgroup.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ee9f0c1..4ed8677 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1427,7 +1427,7 @@ static void init_cgroup_root(struct cgroupfs_root *root) INIT_LIST_HEAD(&root->root_list); root->number_of_cgroups = 1; cgrp->root = root; - cgrp->name = &root_cgroup_name; + RCU_INIT_POINTER(cgrp->name, &root_cgroup_name); init_cgroup_housekeeping(cgrp); } @@ -2558,7 +2558,7 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, return ret; } - old_name = cgrp->name; + old_name = rcu_dereference_protected(cgrp->name, true); rcu_assign_pointer(cgrp->name, name); kfree_rcu(old_name, rcu_head); @@ -4177,13 +4177,15 @@ static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, /* This cgroup is ready now */ for_each_root_subsys(cgrp->root, ss) { struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; + struct css_id *id = rcu_dereference_protected(css->id, true); + /* * Update id->css pointer and make this css visible from * CSS ID functions. This pointer will be dereferened * from RCU-read-side without locks. */ - if (css->id) - rcu_assign_pointer(css->id->css, css); + if (id) + rcu_assign_pointer(id->css, css); } return 0; @@ -4863,7 +4865,7 @@ int __init cgroup_init_early(void) css_set_count = 1; init_cgroup_root(&cgroup_dummy_root); cgroup_root_count = 1; - init_task.cgroups = &init_css_set; + RCU_INIT_POINTER(init_task.cgroups, &init_css_set); init_cgrp_cset_link.cset = &init_css_set; init_cgrp_cset_link.cgrp = cgroup_dummy_top; @@ -5380,7 +5382,8 @@ bool css_is_ancestor(struct cgroup_subsys_state *child, void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) { - struct css_id *id = css->id; + struct css_id *id = rcu_dereference_protected(css->id, true); + /* When this is called before css_id initialization, id can be NULL */ if (!id) return; @@ -5446,8 +5449,8 @@ static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, return PTR_ERR(newid); newid->stack[0] = newid->id; - newid->css = rootcss; - rootcss->id = newid; + RCU_INIT_POINTER(newid->css, rootcss); + RCU_INIT_POINTER(rootcss->id, newid); return 0; } @@ -5461,7 +5464,7 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, subsys_id = ss->subsys_id; parent_css = parent->subsys[subsys_id]; child_css = child->subsys[subsys_id]; - parent_id = parent_css->id; + parent_id = rcu_dereference_protected(parent_css->id, true); depth = parent_id->depth + 1; child_id = get_new_cssid(ss, depth); |