blk-throttle: Take blkcg->lock while traversing blkcg->policy_list

blkcg->policy_list is protected by blkcg->lock. Its not rcu protected
list. So even for readers, they need to take blkcg->lock. There are
few functions which were reading the list without taking lock. Fix it.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 6155367..8f630ce 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -869,60 +869,86 @@ unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
                              dev_t dev)
 {
        struct blkio_policy_node *pn;
+       unsigned long flags;
+       unsigned int weight;
+
+       spin_lock_irqsave(&blkcg->lock, flags);
 
        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
                                BLKIO_PROP_weight_device);
        if (pn)
-               return pn->val.weight;
+               weight = pn->val.weight;
        else
-               return blkcg->weight;
+               weight = blkcg->weight;
+
+       spin_unlock_irqrestore(&blkcg->lock, flags);
+
+       return weight;
 }
 EXPORT_SYMBOL_GPL(blkcg_get_weight);
 
 uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
 {
        struct blkio_policy_node *pn;
+       unsigned long flags;
+       uint64_t bps = -1;
 
+       spin_lock_irqsave(&blkcg->lock, flags);
        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
                                BLKIO_THROTL_read_bps_device);
        if (pn)
-               return pn->val.bps;
-       else
-               return -1;
+               bps = pn->val.bps;
+       spin_unlock_irqrestore(&blkcg->lock, flags);
+
+       return bps;
 }
 
 uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
 {
        struct blkio_policy_node *pn;
+       unsigned long flags;
+       uint64_t bps = -1;
+
+       spin_lock_irqsave(&blkcg->lock, flags);
        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
                                BLKIO_THROTL_write_bps_device);
        if (pn)
-               return pn->val.bps;
-       else
-               return -1;
+               bps = pn->val.bps;
+       spin_unlock_irqrestore(&blkcg->lock, flags);
+
+       return bps;
 }
 
 unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
 {
        struct blkio_policy_node *pn;
+       unsigned long flags;
+       unsigned int iops = -1;
 
+       spin_lock_irqsave(&blkcg->lock, flags);
        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
                                BLKIO_THROTL_read_iops_device);
        if (pn)
-               return pn->val.iops;
-       else
-               return -1;
+               iops = pn->val.iops;
+       spin_unlock_irqrestore(&blkcg->lock, flags);
+
+       return iops;
 }
 
 unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
 {
        struct blkio_policy_node *pn;
+       unsigned long flags;
+       unsigned int iops = -1;
+
+       spin_lock_irqsave(&blkcg->lock, flags);
        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
                                BLKIO_THROTL_write_iops_device);
        if (pn)
-               return pn->val.iops;
-       else
-               return -1;
+               iops = pn->val.iops;
+       spin_unlock_irqrestore(&blkcg->lock, flags);
+
+       return iops;
 }
 
 /* Checks whether user asked for deleting a policy rule */