linux-kernel - Re: [PATCH v3 06/18] ibmvfc: add handlers to drain and complete Sub-CRQ responses

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Message-ID: <3fe8683a-47f6-8713-762a-02c57c2e4ec2@linux.vnet.ibm.com>
Date:   Fri, 4 Dec 2020 08:51:38 -0600
From:   Brian King <brking@...ux.vnet.ibm.com>
To:     Tyrel Datwyler <tyreld@...ux.ibm.com>,
        james.bottomley@...senpartnership.com
Cc:     martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        brking@...ux.ibm.com
Subject: Re: [PATCH v3 06/18] ibmvfc: add handlers to drain and complete
 Sub-CRQ responses

On 12/2/20 8:07 PM, Tyrel Datwyler wrote:
> The logic for iterating over the Sub-CRQ responses is similiar to that
> of the primary CRQ. Add the necessary handlers for processing those
> responses.
> 
> Signed-off-by: Tyrel Datwyler <tyreld@...ux.ibm.com>
> ---
>  drivers/scsi/ibmvscsi/ibmvfc.c | 80 ++++++++++++++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
> index e082935f56cf..b61ae1df21e5 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
> @@ -3381,6 +3381,86 @@ static int ibmvfc_toggle_scrq_irq(struct ibmvfc_sub_queue *scrq, int enable)
>  	return rc;
>  }
>  
> +static void ibmvfc_handle_scrq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost)
> +{
> +	struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba);
> +	unsigned long flags;
> +
> +	switch (crq->valid) {
> +	case IBMVFC_CRQ_CMD_RSP:
> +		break;
> +	case IBMVFC_CRQ_XPORT_EVENT:
> +		return;
> +	default:
> +		dev_err(vhost->dev, "Got and invalid message type 0x%02x\n", crq->valid);
> +		return;
> +	}
> +
> +	/* The only kind of payload CRQs we should get are responses to
> +	 * things we send. Make sure this response is to something we
> +	 * actually sent
> +	 */
> +	if (unlikely(!ibmvfc_valid_event(&vhost->pool, evt))) {
> +		dev_err(vhost->dev, "Returned correlation_token 0x%08llx is invalid!\n",
> +			crq->ioba);
> +		return;
> +	}
> +
> +	if (unlikely(atomic_read(&evt->free))) {
> +		dev_err(vhost->dev, "Received duplicate correlation_token 0x%08llx!\n",
> +			crq->ioba);
> +		return;
> +	}
> +
> +	del_timer(&evt->timer);
> +	list_del(&evt->queue);
> +	ibmvfc_trc_end(evt);> +	spin_unlock_irqrestore(vhost->host->host_lock, flags);

You can't do this here... You are grabbing the host lock in ibmvfc_drain_sub_crq
and saving the irqflags to a local in that function, then doing a spin_unlock_irqrestore
and restoring irqflags using an uninitialized local in this function...

I'm assuming this will get sorted out with the locking changes we've been discussing off-list...


> +	evt->done(evt);
> +	spin_lock_irqsave(vhost->host->host_lock, flags);
> +}
> +
> +static struct ibmvfc_crq *ibmvfc_next_scrq(struct ibmvfc_sub_queue *scrq)
> +{
> +	struct ibmvfc_crq *crq;
> +
> +	crq = &scrq->msgs[scrq->cur].crq;
> +	if (crq->valid & 0x80) {
> +		if (++scrq->cur == scrq->size)
> +			scrq->cur = 0;
> +		rmb();
> +	} else
> +		crq = NULL;
> +
> +	return crq;
> +}
> +
> +static void ibmvfc_drain_sub_crq(struct ibmvfc_sub_queue *scrq)
> +{
> +	struct ibmvfc_crq *crq;
> +	unsigned long flags;
> +	int done = 0;
> +
> +	spin_lock_irqsave(scrq->vhost->host->host_lock, flags);
> +	while (!done) {
> +		while ((crq = ibmvfc_next_scrq(scrq)) != NULL) {
> +			ibmvfc_handle_scrq(crq, scrq->vhost);
> +			crq->valid = 0;
> +			wmb();
> +		}
> +
> +		ibmvfc_toggle_scrq_irq(scrq, 1);
> +		if ((crq = ibmvfc_next_scrq(scrq)) != NULL) {
> +			ibmvfc_toggle_scrq_irq(scrq, 0);
> +			ibmvfc_handle_scrq(crq, scrq->vhost);
> +			crq->valid = 0;
> +			wmb();
> +		} else
> +			done = 1;
> +	}
> +	spin_unlock_irqrestore(scrq->vhost->host->host_lock, flags);
> +}
> +
>  /**
>   * ibmvfc_init_tgt - Set the next init job step for the target
>   * @tgt:		ibmvfc target struct
> 


-- 
Brian King
Power Linux I/O
IBM Linux Technology Center