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authorYu Kuai <yukuai3@huawei.com>2023-01-19 19:03:49 +0800
committerJens Axboe <axboe@kernel.dk>2023-01-29 15:19:04 -0700
commitdfd6200a095440b663099d8d42f1efb0175a1ce3 (patch)
tree5238b2ac06a92d833d47004866e27c2f2bc3346d /block/blk-cgroup.h
parentc7241babf0855d8a6180cd1743ff0ec34de40b4e (diff)
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blk-cgroup: support to track if policy is online
A new field 'online' is added to blkg_policy_data to fix following 2 problem: 1) In blkcg_activate_policy(), if pd_alloc_fn() with 'GFP_NOWAIT' failed, 'queue_lock' will be dropped and pd_alloc_fn() will try again without 'GFP_NOWAIT'. In the meantime, remove cgroup can race with it, and pd_offline_fn() will be called without pd_init_fn() and pd_online_fn(). This way null-ptr-deference can be triggered. 2) In order to synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy(), 'list_del_init(&blkg->q_node)' will be delayed to blkg_free_workfn(), hence pd_offline_fn() can be called first in blkg_destroy(), and then blkcg_deactivate_policy() will call it again, we must prevent it. The new field 'online' will be set after pd_online_fn() and will be cleared after pd_offline_fn(), in the meantime pd_offline_fn() will only be called if 'online' is set. Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20230119110350.2287325-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-cgroup.h')
-rw-r--r--block/blk-cgroup.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 1e94e404eaa8..b13ee84f358e 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -135,6 +135,7 @@ struct blkg_policy_data {
/* the blkg and policy id this per-policy data belongs to */
struct blkcg_gq *blkg;
int plid;
+ bool online;
};
/*