From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
axboe@kernel.dk, sagi@grimberg.me
Subject: Re: [PATCHv2 3/3] nvme-pci: fix queue_rqs list splitting
Date: Tue, 4 Jan 2022 11:38:07 -0800 [thread overview]
Message-ID: <20220104193807.GB2666557@dhcp-10-100-145-180.wdc.com> (raw)
In-Reply-To: <20211229174602.GC28058@lst.de>
On Wed, Dec 29, 2021 at 06:46:02PM +0100, Christoph Hellwig wrote:
> I wonder if a restart label here would be a little cleaner, something
> like:
On second thought, this requires another check that the *rqlist is not
NULL before 'goto restart' since the safe iterator dereferences it. I'm
not sure this is cleaner than the original anymore.
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 992ee314e91ba..29b433fd12bdd 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -999,9 +999,11 @@ static bool nvme_prep_rq_batch(struct nvme_queue *nvmeq, struct request *req)
>
> static void nvme_queue_rqs(struct request **rqlist)
> {
> - struct request *req, *next, *prev = NULL;
> + struct request *req, *next, *prev;
> struct request *requeue_list = NULL;
>
> +restart:
> + prev = NULL;
> rq_list_for_each_safe(rqlist, req, next) {
> struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
>
> @@ -1009,9 +1011,9 @@ static void nvme_queue_rqs(struct request **rqlist)
> /* detach 'req' and add to remainder list */
> rq_list_move(rqlist, &requeue_list, req, prev, next);
>
> + if (!prev)
> + break;
> req = prev;
> - if (!req)
> - continue;
> }
>
> if (!next || req->mq_hctx != next->mq_hctx) {
> @@ -1019,9 +1021,9 @@ static void nvme_queue_rqs(struct request **rqlist)
> req->rq_next = NULL;
> nvme_submit_cmds(nvmeq, rqlist);
> *rqlist = next;
> - prev = NULL;
> - } else
> - prev = req;
> + goto restart;
> + }
> + prev = req;
> }
>
> *rqlist = requeue_list;
next prev parent reply other threads:[~2022-01-04 19:38 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-27 16:41 [PATCHv2 1/3] block: introduce rq_list_for_each_safe macro Keith Busch
2021-12-27 16:41 ` [PATCHv2 2/3] block: introduce rq_list_move Keith Busch
2021-12-27 18:49 ` kernel test robot
2021-12-27 18:49 ` kernel test robot
2021-12-29 17:41 ` Christoph Hellwig
2021-12-29 20:59 ` Keith Busch
2021-12-27 16:41 ` [PATCHv2 3/3] nvme-pci: fix queue_rqs list splitting Keith Busch
2021-12-29 17:46 ` Christoph Hellwig
2021-12-29 21:04 ` Keith Busch
2021-12-30 7:53 ` Christoph Hellwig
2022-01-04 19:38 ` Keith Busch [this message]
2022-01-05 7:35 ` Christoph Hellwig
2021-12-29 17:39 ` [PATCHv2 1/3] block: introduce rq_list_for_each_safe macro Christoph Hellwig
2021-12-29 20:57 ` Keith Busch
2021-12-30 14:38 ` Max Gurtovoy
2021-12-30 15:30 ` Keith Busch
2022-01-03 15:23 ` Max Gurtovoy
2022-01-03 18:15 ` Keith Busch
2022-01-04 12:15 ` Max Gurtovoy
2022-01-05 17:26 ` Keith Busch
2022-01-06 11:54 ` Max Gurtovoy
2022-01-06 13:41 ` Jens Axboe
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