linux-kernel - Re: [PATCH] lightnvm: update closed list out of interrupt context

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Message-ID: <56A770BD.8050602@lightnvm.io>
Date:	Tue, 26 Jan 2016 14:12:29 +0100
From:	Matias Bjørling <mb@...htnvm.io>
To:	Javier González <jg@...htnvm.io>
Cc:	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	Javier González <javier@...xlabs.com>
Subject: Re: [PATCH] lightnvm: update closed list out of interrupt context

On 01/25/2016 12:58 PM, Javier González wrote:
> When an I/O finishes, full blocks are moved from the open to the closed
> list - a lock is taken to protect the list. This happens at the moment
> in the interrupt context, which is not correct.
> 
> This patch moves this logic to the GC workqueue instead, thus avoiding
> holding a spinlock in an atomic context.
> 
> Signed-off-by: Javier González <javier@...xlabs.com>
> ---
>  drivers/lightnvm/rrpc.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
> index d8c7595..e2710da 100644
> --- a/drivers/lightnvm/rrpc.c
> +++ b/drivers/lightnvm/rrpc.c
> @@ -497,12 +497,21 @@ static void rrpc_gc_queue(struct work_struct *work)
>  	struct rrpc *rrpc = gcb->rrpc;
>  	struct rrpc_block *rblk = gcb->rblk;
>  	struct nvm_lun *lun = rblk->parent->lun;
> +	struct nvm_block *blk = rblk->parent;
>  	struct rrpc_lun *rlun = &rrpc->luns[lun->id - rrpc->lun_offset];
>  
>  	spin_lock(&rlun->lock);
>  	list_add_tail(&rblk->prio, &rlun->prio_list);
>  	spin_unlock(&rlun->lock);
>  
> +	spin_lock(&lun->lock);
> +	lun->nr_open_blocks--;
> +	lun->nr_closed_blocks++;
> +	blk->state &= ~NVM_BLK_ST_OPEN;
> +	blk->state |= NVM_BLK_ST_CLOSED;
> +	list_move_tail(&rblk->list, &rlun->closed_list);
> +	spin_unlock(&lun->lock);
> +
>  	mempool_free(gcb, rrpc->gcb_pool);
>  	pr_debug("nvm: block '%lu' is full, allow GC (sched)\n",
>  							rblk->parent->id);
> @@ -666,20 +675,8 @@ static void rrpc_end_io_write(struct rrpc *rrpc, struct rrpc_rq *rrqd,
>  		lun = rblk->parent->lun;
>  
>  		cmnt_size = atomic_inc_return(&rblk->data_cmnt_size);
> -		if (unlikely(cmnt_size == rrpc->dev->pgs_per_blk)) {
> -			struct nvm_block *blk = rblk->parent;
> -			struct rrpc_lun *rlun = rblk->rlun;
> -
> -			spin_lock(&lun->lock);
> -			lun->nr_open_blocks--;
> -			lun->nr_closed_blocks++;
> -			blk->state &= ~NVM_BLK_ST_OPEN;
> -			blk->state |= NVM_BLK_ST_CLOSED;
> -			list_move_tail(&rblk->list, &rlun->closed_list);
> -			spin_unlock(&lun->lock);
> -
> +		if (unlikely(cmnt_size == rrpc->dev->pgs_per_blk))
>  			rrpc_run_gc(rrpc, rblk);
> -		}
>  	}
>  }
>  
> 

Thanks, applied. I have updated the patch text a bit and added Fixes:
field to mark the patch a fix for the ff0e498b "lightnvm: manage open
and closed blocks separately".