From: Damien Le Moal <damien.lemoal@opensource.wdc.com>
To: John Garry <john.garry@huawei.com>,
axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com,
jinpu.wang@cloud.ionos.com, hare@suse.de, bvanassche@acm.org,
hch@lst.de, ming.lei@redhat.com, niklas.cassel@wdc.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
linuxarm@huawei.com
Subject: Re: [PATCH RFC v3 01/22] blk-mq: Don't get budget for reserved requests
Date: Thu, 27 Oct 2022 10:16:43 +0900 [thread overview]
Message-ID: <9cd8aa6a-98be-ddba-db4e-07ed59b53f08@opensource.wdc.com> (raw)
In-Reply-To: <1666693096-180008-2-git-send-email-john.garry@huawei.com>
On 10/25/22 19:17, John Garry wrote:
> It should be possible to send reserved requests even when there is no
> budget, so don't request a budget in that case.
>
> This comes into play when we need to allocate a reserved request from the
> target device request queue for error handling for that same device.
>
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
> block/blk-mq.c | 4 +++-
> drivers/scsi/scsi_lib.c | 3 ++-
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 260adeb2e455..d8baabb32ea4 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1955,11 +1955,13 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> errors = queued = 0;
> do {
> struct blk_mq_queue_data bd;
> + bool need_budget;
>
> rq = list_first_entry(list, struct request, queuelist);
>
> WARN_ON_ONCE(hctx != rq->mq_hctx);
> - prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
> + need_budget = !nr_budgets && !blk_mq_is_reserved_rq(rq);
> + prep = blk_mq_prep_dispatch_rq(rq, need_budget);
> if (prep != PREP_DISPATCH_OK)
> break;
Below this code, there is:
if (nr_budgets)
nr_budgets--;
Don't you need to change that to:
if (need_budget && nr_budgets)
nr_budgets--;
? Otherwise, the accounting will be off.
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index fa96d3cfdfa3..39d4fd124375 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -298,7 +298,8 @@ void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd)
> if (starget->can_queue > 0)
> atomic_dec(&starget->target_busy);
>
> - sbitmap_put(&sdev->budget_map, cmd->budget_token);
> + if (!blk_mq_is_reserved_rq(scsi_cmd_to_rq(cmd)))
> + sbitmap_put(&sdev->budget_map, cmd->budget_token);
> cmd->budget_token = -1;
> }
>
--
Damien Le Moal
Western Digital Research
next prev parent reply other threads:[~2022-10-27 1:16 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 10:17 [PATCH RFC v3 00/22] blk-mq/libata/scsi: SCSI driver tagging improvements Part I John Garry
2022-10-25 10:11 ` John Garry
2022-10-25 10:17 ` [PATCH RFC v3 01/22] blk-mq: Don't get budget for reserved requests John Garry
2022-10-27 1:16 ` Damien Le Moal [this message]
2022-10-27 9:09 ` John Garry
2022-10-25 10:17 ` [PATCH RFC v3 02/22] scsi: core: Add scsi_get_dev() John Garry
2022-10-25 10:17 ` [PATCH RFC v3 03/22] scsi: core: Implement reserved command handling John Garry
2022-10-27 1:18 ` Damien Le Moal
2022-10-27 7:51 ` Hannes Reinecke
2022-10-27 8:16 ` John Garry
2022-10-27 9:11 ` John Garry
2022-10-25 10:17 ` [PATCH RFC v3 04/22] scsi: core: Add support to send reserved commands John Garry
2022-10-27 1:21 ` Damien Le Moal
2022-10-27 9:13 ` John Garry
2022-10-27 9:18 ` Damien Le Moal
2022-10-25 10:17 ` [PATCH RFC v3 05/22] scsi: core: Add support for reserved command timeout handling John Garry
2022-10-25 10:18 ` [PATCH RFC v3 06/22] scsi: libsas: Improve sas_ex_discover_expander() error handling John Garry
2022-10-25 10:18 ` [PATCH RFC v3 07/22] scsi: libsas: Notify LLDD expander found before calling sas_rphy_add() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 08/22] scsi: scsi_transport_sas: Alloc sdev for expander John Garry
2022-10-25 10:18 ` [PATCH RFC v3 09/22] scsi: libsas: Add sas_alloc_slow_task_rq() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 10/22] scsi: libsas: Add sas_queuecommand_internal() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 11/22] scsi: libsas: Add sas_internal_timeout() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 12/22] scsi: core: Use SCSI_SCAN_RESCAN in __scsi_add_device() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 13/22] scsi: scsi_transport_sas: Allocate end device target id in the rphy alloc John Garry
2022-10-25 10:18 ` [PATCH RFC v3 14/22] ata: libata-scsi: Add ata_scsi_setup_sdev() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 15/22] scsi: libsas: Add sas_ata_setup_device() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 16/22] ata: libata-scsi: Allocate sdev early in port probe John Garry
2022-10-27 1:34 ` Damien Le Moal
2022-10-27 8:11 ` Hannes Reinecke
2022-10-27 9:16 ` Damien Le Moal
2022-10-27 9:51 ` Hannes Reinecke
2022-11-07 10:09 ` John Garry
2022-11-07 10:20 ` Hannes Reinecke
2022-10-25 10:18 ` [PATCH RFC v3 17/22] scsi: libsas drivers: Reserve tags John Garry
2022-10-25 10:18 ` [PATCH RFC v3 18/22] scsi: libsas: Queue SMP commands as requests John Garry
2022-10-27 1:36 ` Damien Le Moal
2022-10-27 10:45 ` John Garry
2022-10-25 10:18 ` [PATCH RFC v3 19/22] scsi: libsas: Queue TMF " John Garry
2022-10-25 10:18 ` [PATCH RFC v3 20/22] scsi: core: Add scsi_alloc_request_hwq() John Garry
2022-10-25 10:18 ` [PATCH RFC v3 21/22] scsi: libsas: Queue internal abort commands as requests John Garry
2022-10-29 1:15 ` chenxiang (M)
2022-11-02 10:04 ` John Garry
2022-11-03 3:09 ` chenxiang (M)
2022-10-25 10:18 ` [PATCH RFC v3 22/22] scsi: libsas: Delete sas_task_slow.timer John Garry
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