Messages in this thread | | | Subject | Re: [PATCH -next v2 8/9] block: fix null-pointer dereference in ioc_pd_init | From | Yu Kuai <> | Date | Thu, 1 Dec 2022 18:23:16 +0800 |
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Hi,
在 2022/12/01 18:11, Tejun Heo 写道: > On Thu, Dec 01, 2022 at 10:12:13AM +0800, Yu Kuai wrote: >> 1) By mentioning that "del_gendisk() is quiescing the queue", do you >> suggest to add rcu_read_lock()? This seems wrong because blk_iocost_init >> requires memory allocation. > > Quiescing uses SRCU so that should be fine but I'm not sure whether this is > the right one to piggyback on. Jens should have a better idea. > > Thanks. >
Currently SRCU is used if BLK_MQ_F_BLOCKING set, otherwise RCU is used.
dispatch: #define __blk_mq_run_dispatch_ops(q, check_sleep, dispatch_ops) \ do { \ if ((q)->tag_set->flags & BLK_MQ_F_BLOCKING) { \ int srcu_idx; \ \ might_sleep_if(check_sleep); \ srcu_idx = srcu_read_lock((q)->tag_set->srcu); \ (dispatch_ops); \ srcu_read_unlock((q)->tag_set->srcu, srcu_idx); \ } else { \ rcu_read_lock(); \ (dispatch_ops); \ rcu_read_unlock(); \ } \ } while (0)
quiesce: void blk_mq_wait_quiesce_done(struct blk_mq_tag_set *set) { if (set->flags & BLK_MQ_F_BLOCKING) synchronize_srcu(set->srcu); else synchronize_rcu(); }
Thanks, Kuai
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