linux-kernel - Re: [PATCH 2/6] hisi_sas: add hisi_sas_slot

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Date:	Tue, 16 Feb 2016 16:22:42 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	John Garry <john.garry@...wei.com>, JBottomley@...n.com,
	martin.petersen@...cle.com
Cc:	linuxarm@...wei.com, zhangfei.gao@...aro.org, xuwei5@...ilicon.com,
	john.garry2@...l.dcu.ie, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] hisi_sas: add hisi_sas_slot_abort()

On 02/16/2016 01:22 PM, John Garry wrote:
> Add a function to abort a slot (task) in the device
> (if it is in the task set) and then cleanup and
> complete the task.
> The function is called from work queue context as
> it cannot be called from the context where it is
> triggered (interrupt).
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  drivers/scsi/hisi_sas/hisi_sas.h      |  1 +
>  drivers/scsi/hisi_sas/hisi_sas_main.c | 43 +++++++++++++++++++++++++++++++++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
> index 02da7e4..a05ce71 100644
> --- a/drivers/scsi/hisi_sas/hisi_sas.h
> +++ b/drivers/scsi/hisi_sas/hisi_sas.h
> @@ -120,6 +120,7 @@ struct hisi_sas_slot {
>  	dma_addr_t command_table_dma;
>  	struct hisi_sas_sge_page *sge_page;
>  	dma_addr_t sge_page_dma;
> +	struct work_struct abort_slot;
>  };
>  
>  struct hisi_sas_tmf_task {
> diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
> index c600f5e..65509eb 100644
> --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
> +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
> @@ -15,6 +15,9 @@
>  #define DEV_IS_GONE(dev) \
>  	((!dev) || (dev->dev_type == SAS_PHY_UNUSED))
>  
> +static int hisi_sas_debug_issue_ssp_tmf(struct domain_device *device,
> +				u8 *lun, struct hisi_sas_tmf_task *tmf);
> +
>  static struct hisi_hba *dev_to_hisi_hba(struct domain_device *device)
>  {
>  	return device->port->ha->lldd_ha;
> @@ -113,6 +116,45 @@ static int hisi_sas_task_prep_ata(struct hisi_hba *hisi_hba,
>  	return hisi_hba->hw->prep_stp(hisi_hba, slot);
>  }
>  
> +/*
> + * This function will issue an abort TMF if a task is still in
> + * the target. Then it will do the task complete cleanup and
> + * callbacks.
> + */
> +static void hisi_sas_slot_abort(struct work_struct *work)
> +{
> +	struct hisi_sas_slot *abort_slot =
> +		container_of(work, struct hisi_sas_slot, abort_slot);
> +	struct sas_task *task = abort_slot->task;
> +	struct hisi_hba *hisi_hba = dev_to_hisi_hba(task->dev);
> +	struct scsi_cmnd *cmnd = task->uldd_task;
> +	struct hisi_sas_tmf_task tmf_task;
> +	struct domain_device *device = task->dev;
> +	struct hisi_sas_device *sas_dev = device->lldd_dev;
> +	struct scsi_lun lun;
> +	int tag = abort_slot->idx, rc;
> +
> +	int_to_scsilun(cmnd->device->lun, &lun);
> +	tmf_task.tmf = TMF_QUERY_TASK;
> +	tmf_task.tag_of_task_to_be_managed = cpu_to_le16(tag);
> +
> +	rc = hisi_sas_debug_issue_ssp_tmf(task->dev, lun.scsi_lun, &tmf_task);
> +
> +	/* TMF_RESP_FUNC_SUCC means task is present in the task set */
> +	if (rc != TMF_RESP_FUNC_SUCC)
> +		goto out;
> +	tmf_task.tmf = TMF_ABORT_TASK;
> +	tmf_task.tag_of_task_to_be_managed = cpu_to_le16(tag);
> +
> +	rc = hisi_sas_debug_issue_ssp_tmf(task->dev, lun.scsi_lun, &tmf_task);
> +out:
> +	hisi_sas_slot_task_free(hisi_hba, task, abort_slot);
> +	if (task->task_done)
> +		task->task_done(task);
> +	if (sas_dev && sas_dev->running_req)
> +		sas_dev->running_req--;
> +}
> +
>  static int hisi_sas_task_prep(struct sas_task *task, struct hisi_hba *hisi_hba,
>  			      int is_tmf, struct hisi_sas_tmf_task *tmf,
>  			      int *pass)
Do you really need to query the task first?
As per SAM a successful return from an ABORT TASK TMF has this meaning:

A response of FUNCTION COMPLETE shall indicate that the task was
aborted or was not in the task set.

Ie it doesn't matter if the task was present or not.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@...e.de			               +49 911 74053 688
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