Messages in this thread | | | Date | Mon, 14 Nov 2022 12:07:45 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH v2 4/5] blk-iocost: fix sleeping in atomic context warnning |
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On Fri, Nov 04, 2022 at 10:39:37AM +0800, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > match_u64() is called inside ioc->lock, which causes smatch static > checker warnings: > > block/blk-iocost.c:3211 ioc_qos_write() warn: sleeping in atomic context > block/blk-iocost.c:3240 ioc_qos_write() warn: sleeping in atomic context > block/blk-iocost.c:3407 ioc_cost_model_write() warn: sleeping in atomic > context > > Fix the problem by introducing a mutex and using it while prasing input > params.
It bothers me that parsing an u64 string requires a GFP_KERNEL memory allocation.
> @@ -2801,9 +2806,11 @@ static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos) > { > struct ioc *ioc = rqos_to_ioc(rqos); > > + mutex_lock(&ioc->params_mutex); > spin_lock_irq(&ioc->lock); > ioc_refresh_params(ioc, false); > spin_unlock_irq(&ioc->lock); > + mutex_unlock(&ioc->params_mutex); > }
Aren't the params still protected by ioc->lock? Why do we need to grab both?
Any chance I can persuade you into updating match_NUMBER() helpers to not use match_strdup()? They can easily disable irq/preemption and use percpu buffers and we won't need most of this patchset.
Thanks.
-- tejun
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