blkcg: implement all_blkcgs list
Add all_blkcgs list goes through blkcg->all_blkcgs_node and is
protected by blkcg_pol_mutex. This will be used to fix
blkcg_policy_data allocation bug.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 05b893d..42ff436 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -46,6 +46,8 @@
static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
+static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
+
static bool blkcg_policy_enabled(struct request_queue *q,
const struct blkcg_policy *pol)
{
@@ -817,6 +819,10 @@
{
struct blkcg *blkcg = css_to_blkcg(css);
+ mutex_lock(&blkcg_pol_mutex);
+ list_del(&blkcg->all_blkcgs_node);
+ mutex_unlock(&blkcg_pol_mutex);
+
if (blkcg != &blkcg_root) {
int i;
@@ -833,6 +839,8 @@
struct cgroup_subsys_state *ret;
int i;
+ mutex_lock(&blkcg_pol_mutex);
+
if (!parent_css) {
blkcg = &blkcg_root;
goto done;
@@ -844,8 +852,6 @@
goto free_blkcg;
}
- mutex_lock(&blkcg_pol_mutex);
-
for (i = 0; i < BLKCG_MAX_POLS ; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
struct blkcg_policy_data *cpd;
@@ -862,7 +868,6 @@
BUG_ON(blkcg->pd[i]);
cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
if (!cpd) {
- mutex_unlock(&blkcg_pol_mutex);
ret = ERR_PTR(-ENOMEM);
goto free_pd_blkcg;
}
@@ -871,7 +876,6 @@
pol->cpd_init_fn(blkcg);
}
- mutex_unlock(&blkcg_pol_mutex);
done:
spin_lock_init(&blkcg->lock);
INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
@@ -879,14 +883,17 @@
#ifdef CONFIG_CGROUP_WRITEBACK
INIT_LIST_HEAD(&blkcg->cgwb_list);
#endif
+ list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);
+
+ mutex_unlock(&blkcg_pol_mutex);
return &blkcg->css;
free_pd_blkcg:
for (i--; i >= 0; i--)
kfree(blkcg->pd[i]);
-
free_blkcg:
kfree(blkcg);
+ mutex_unlock(&blkcg_pol_mutex);
return ret;
}