blkcg: Fix multiple bugs in blkcg_activate_policy()
blkcg_activate_policy() has the following bugs. * cf09a8ee ("blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()") added @blkcg to ->pd_alloc_fn(); however, blkcg_activate_policy() ends up using pd's allocated for the root blkcg for all preallocations, so ->pd_init_fn() for non-root blkcgs can be passed in pd's which are allocated for the root blkcg. For blk-iocost, this means that ->pd_init_fn() can write beyond the end of the allocated object as it determines the length of the flex array at the end based on the blkcg's nesting level. * Each pd is initialized as they get allocated. If alloc fails, the policy will get freed with pd's initialized on it. * After the above partial failure, the partial pds are not freed. This patch fixes all the above issues by * Restructuring blkcg_activate_policy() so that alloc and init passes are separate. Init takes place only after all allocs succeeded and on failure all allocated pds are freed. * Unifying and fixing the cleanup of the remaining pd_prealloc. Signed-off-by:Tejun Heo <tj@kernel.org> Fixes: cf09a8ee ("blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()") Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
5da0fb1a
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