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Subject: Re: [PATCH v3 06/18] ibmvfc: add handlers to drain and complete
 Sub-CRQ responses
To:     Brian King <brking@linux.vnet.ibm.com>,
        james.bottomley@hansenpartnership.com
Cc:     martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        brking@linux.ibm.com
References: <20201203020806.14747-1-tyreld@linux.ibm.com>
 <20201203020806.14747-7-tyreld@linux.ibm.com>
 <3fe8683a-47f6-8713-762a-02c57c2e4ec2@linux.vnet.ibm.com>
From:   Tyrel Datwyler <tyreld@linux.ibm.com>
Message-ID: <1961b4e3-0732-ac5c-e691-2fa02218ac35@linux.ibm.com>
Date:   Fri, 4 Dec 2020 16:16:48 -0800
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On 12/4/20 6:51 AM, Brian King wrote:
> 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@linux.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...

Correct, moving to per-queue locks and flags stored in the queue struct.

-Tyrel

> 
> 
>> +	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
>>
> 
>