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* [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template
@ 2019-05-02  0:47 Tyrel Datwyler
  2019-05-02  0:47 ` [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states Tyrel Datwyler
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Tyrel Datwyler @ 2019-05-02  0:47 UTC (permalink / raw)
  To: james.bottomley
  Cc: Tyrel Datwyler, martin.petersen, linux-scsi, Tyrel Datwyler,
	brking, linuxppc-dev

From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>

Wire up the host_reset function in our driver_template to allow a user
requested adpater reset via the host_reset sysfs attribute.

Example:

echo "adapter" > /sys/class/scsi_host/host0/host_reset

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 8cec5230fe31..1c37244f16a0 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -2050,6 +2050,18 @@ static struct device_attribute ibmvscsi_host_config = {
 	.show = show_host_config,
 };
 
+static int ibmvscsi_host_reset(struct Scsi_Host *shost, int reset_type)
+{
+	struct ibmvscsi_host_data *hostdata = shost_priv(shost);
+
+	vio_disable_interrupts(to_vio_dev(hostdata->dev));
+	dev_info(hostdata->dev, "Initiating adapter reset!\n");
+	ibmvscsi_reset_host(hostdata);
+	vio_enable_interrupts(to_vio_dev(hostdata->dev));
+
+	return 0;
+}
+
 static struct device_attribute *ibmvscsi_attrs[] = {
 	&ibmvscsi_host_vhost_loc,
 	&ibmvscsi_host_vhost_name,
@@ -2076,6 +2088,7 @@ static struct scsi_host_template driver_template = {
 	.eh_host_reset_handler = ibmvscsi_eh_host_reset_handler,
 	.slave_configure = ibmvscsi_slave_configure,
 	.change_queue_depth = ibmvscsi_change_queue_depth,
+	.host_reset = ibmvscsi_host_reset,
 	.cmd_per_lun = IBMVSCSI_CMDS_PER_LUN_DEFAULT,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,
-- 
2.18.1

^ permalink raw reply related	[flat|nested] 7+ messages in thread

* [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states
  2019-05-02  0:47 [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Tyrel Datwyler
@ 2019-05-02  0:47 ` Tyrel Datwyler
  2019-05-02 21:43   ` Brian King
  2019-05-02  0:47 ` [PATCH 3/3] ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON Tyrel Datwyler
  2019-05-02 21:50 ` [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Brian King
  2 siblings, 1 reply; 7+ messages in thread
From: Tyrel Datwyler @ 2019-05-02  0:47 UTC (permalink / raw)
  To: james.bottomley
  Cc: Tyrel Datwyler, martin.petersen, linux-scsi, Tyrel Datwyler,
	brking, linuxppc-dev

From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>

The current implemenation relies on two flags in the drivers private host
structure to signal the need for a host reset or to reenable the CRQ after a
LPAR migration. This patch does away with those flags and introduces a single
action flag and defined enums for the supported kthread work actions. Lastly,
the if/else logic is replaced with a switch statement.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c | 57 +++++++++++++++++++++-----------
 drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
 2 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 1c37244f16a0..683139e6c63f 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -828,7 +828,7 @@ static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
 	atomic_set(&hostdata->request_limit, 0);
 
 	purge_requests(hostdata, DID_ERROR);
-	hostdata->reset_crq = 1;
+	hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
 	wake_up(&hostdata->work_wait_q);
 }
 
@@ -1797,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
 			/* We need to re-setup the interpartition connection */
 			dev_info(hostdata->dev, "Re-enabling adapter!\n");
 			hostdata->client_migrated = 1;
-			hostdata->reenable_crq = 1;
+			hostdata->action = IBMVSCSI_HOST_ACTION_REENABLE;
 			purge_requests(hostdata, DID_REQUEUE);
 			wake_up(&hostdata->work_wait_q);
 		} else {
@@ -2118,26 +2118,32 @@ static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
 
 static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
 {
+	unsigned long flags;
 	int rc;
 	char *action = "reset";
 
-	if (hostdata->reset_crq) {
-		smp_rmb();
-		hostdata->reset_crq = 0;
-
+	spin_lock_irqsave(hostdata->host->host_lock, flags);
+	switch (hostdata->action) {
+	case IBMVSCSI_HOST_ACTION_NONE:
+		break;
+	case IBMVSCSI_HOST_ACTION_RESET:
 		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
 		if (!rc)
 			rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
 		vio_enable_interrupts(to_vio_dev(hostdata->dev));
-	} else if (hostdata->reenable_crq) {
-		smp_rmb();
+		break;
+	case IBMVSCSI_HOST_ACTION_REENABLE:
 		action = "enable";
 		rc = ibmvscsi_reenable_crq_queue(&hostdata->queue, hostdata);
-		hostdata->reenable_crq = 0;
 		if (!rc)
 			rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
-	} else
-		return;
+		break;
+	default:
+		break;
+	}
+
+	hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
+	spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 
 	if (rc) {
 		atomic_set(&hostdata->request_limit, -1);
@@ -2147,19 +2153,32 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
 	scsi_unblock_requests(hostdata->host);
 }
 
-static int ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
+static int __ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
 {
 	if (kthread_should_stop())
 		return 1;
-	else if (hostdata->reset_crq) {
-		smp_rmb();
-		return 1;
-	} else if (hostdata->reenable_crq) {
-		smp_rmb();
-		return 1;
+	switch (hostdata->action) {
+	case IBMVSCSI_HOST_ACTION_NONE:
+		return 0;
+	case IBMVSCSI_HOST_ACTION_RESET:
+	case IBMVSCSI_HOST_ACTION_REENABLE:
+	default:
+		break;
 	}
 
-	return 0;
+	return 1;
+}
+
+static int ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(hostdata->host->host_lock, flags);
+	rc = __ibmvscsi_work_to_do(hostdata);
+	spin_unlock_irqrestore(hostdata->host->host_lock, flags);
+
+	return rc;
 }
 
 static int ibmvscsi_work(void *data)
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.h b/drivers/scsi/ibmvscsi/ibmvscsi.h
index 3a7875575616..04bcbc832dc9 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -88,13 +88,18 @@ struct event_pool {
 	dma_addr_t iu_token;
 };
 
+enum ibmvscsi_host_action {
+	IBMVSCSI_HOST_ACTION_NONE = 0,
+	IBMVSCSI_HOST_ACTION_RESET,
+	IBMVSCSI_HOST_ACTION_REENABLE,
+};
+
 /* all driver data associated with a host adapter */
 struct ibmvscsi_host_data {
 	struct list_head host_list;
 	atomic_t request_limit;
 	int client_migrated;
-	int reset_crq;
-	int reenable_crq;
+	enum ibmvscsi_host_action action;
 	struct device *dev;
 	struct event_pool pool;
 	struct crq_queue queue;
-- 
2.18.1

^ permalink raw reply related	[flat|nested] 7+ messages in thread

* [PATCH 3/3] ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON
  2019-05-02  0:47 [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Tyrel Datwyler
  2019-05-02  0:47 ` [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states Tyrel Datwyler
@ 2019-05-02  0:47 ` Tyrel Datwyler
  2019-05-02 21:50 ` [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Brian King
  2 siblings, 0 replies; 7+ messages in thread
From: Tyrel Datwyler @ 2019-05-02  0:47 UTC (permalink / raw)
  To: james.bottomley
  Cc: Tyrel Datwyler, martin.petersen, linux-scsi, Tyrel Datwyler,
	brking, linuxppc-dev

From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>

After a successful SRP login response we call scsi_unblock_requests() to
kick any pending IO's. The callback to process this SRP response happens in
a tasklet and therefore is in softirq context. The result of such is
that when blk-mq is enabled it is no longer safe to call
scsi_unblock_requests() from this context. The result of duing so
triggers the following WARN_ON splat in dmesg after a host reset or CRQ
reenablement.

WARNING: CPU: 0 PID: 0 at block/blk-mq.c:1375 __blk_mq_run_hw_queue+0x120/0x180
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.0.0-rc8 #4
NIP [c0000000009771e0] __blk_mq_run_hw_queue+0x120/0x180
LR [c000000000977484] __blk_mq_delay_run_hw_queue+0x244/0x250
Call Trace:

__blk_mq_delay_run_hw_queue+0x244/0x250
blk_mq_run_hw_queue+0x8c/0x1c0
blk_mq_run_hw_queues+0x60/0x90
scsi_run_queue+0x1e4/0x3b0
scsi_run_host_queues+0x48/0x80
login_rsp+0xb0/0x100
ibmvscsi_handle_crq+0x30c/0x3e0
ibmvscsi_task+0x54/0xe0
tasklet_action_common.isra.3+0xc4/0x1a0
__do_softirq+0x174/0x3f4
irq_exit+0xf0/0x120
__do_irq+0xb0/0x210
call_do_irq+0x14/0x24
do_IRQ+0x9c/0x130
hardware_interrupt_common+0x14c/0x150

This patch fixes the issue by introducing a new host action for
unblocking the scsi requests in our seperate work thread.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c | 5 ++++-
 drivers/scsi/ibmvscsi/ibmvscsi.h | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 683139e6c63f..c1d83eb5c5f7 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1179,7 +1179,8 @@ static void login_rsp(struct srp_event_struct *evt_struct)
 		   be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta));
 
 	/* If we had any pending I/Os, kick them */
-	scsi_unblock_requests(hostdata->host);
+	hostdata->action = IBMVSCSI_HOST_ACTION_UNBLOCK;
+	wake_up(&hostdata->work_wait_q);
 }
 
 /**
@@ -2125,6 +2126,7 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
 	spin_lock_irqsave(hostdata->host->host_lock, flags);
 	switch (hostdata->action) {
 	case IBMVSCSI_HOST_ACTION_NONE:
+	case IBMVSCSI_HOST_ACTION_UNBLOCK:
 		break;
 	case IBMVSCSI_HOST_ACTION_RESET:
 		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
@@ -2162,6 +2164,7 @@ static int __ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
 		return 0;
 	case IBMVSCSI_HOST_ACTION_RESET:
 	case IBMVSCSI_HOST_ACTION_REENABLE:
+	case IBMVSCSI_HOST_ACTION_UNBLOCK:
 	default:
 		break;
 	}
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.h b/drivers/scsi/ibmvscsi/ibmvscsi.h
index 04bcbc832dc9..d9bf502334ba 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -92,6 +92,7 @@ enum ibmvscsi_host_action {
 	IBMVSCSI_HOST_ACTION_NONE = 0,
 	IBMVSCSI_HOST_ACTION_RESET,
 	IBMVSCSI_HOST_ACTION_REENABLE,
+	IBMVSCSI_HOST_ACTION_UNBLOCK,
 };
 
 /* all driver data associated with a host adapter */
-- 
2.18.1

^ permalink raw reply related	[flat|nested] 7+ messages in thread

* Re: [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states
  2019-05-02  0:47 ` [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states Tyrel Datwyler
@ 2019-05-02 21:43   ` Brian King
  2019-05-03  0:35     ` Tyrel Datwyler
  0 siblings, 1 reply; 7+ messages in thread
From: Brian King @ 2019-05-02 21:43 UTC (permalink / raw)
  To: Tyrel Datwyler, james.bottomley
  Cc: brking, linuxppc-dev, linux-scsi, martin.petersen, Tyrel Datwyler

On 5/1/19 7:47 PM, Tyrel Datwyler wrote:
> From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
> 
> The current implemenation relies on two flags in the drivers private host
> structure to signal the need for a host reset or to reenable the CRQ after a
> LPAR migration. This patch does away with those flags and introduces a single
> action flag and defined enums for the supported kthread work actions. Lastly,
> the if/else logic is replaced with a switch statement.
> 
> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
> ---
>  drivers/scsi/ibmvscsi/ibmvscsi.c | 57 +++++++++++++++++++++-----------
>  drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
>  2 files changed, 45 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 1c37244f16a0..683139e6c63f 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -828,7 +828,7 @@ static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
>  	atomic_set(&hostdata->request_limit, 0);
>  
>  	purge_requests(hostdata, DID_ERROR);
> -	hostdata->reset_crq = 1;
> +	hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
>  	wake_up(&hostdata->work_wait_q);
>  }
>  
> @@ -1797,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
>  			/* We need to re-setup the interpartition connection */
>  			dev_info(hostdata->dev, "Re-enabling adapter!\n");
>  			hostdata->client_migrated = 1;
> -			hostdata->reenable_crq = 1;
> +			hostdata->action = IBMVSCSI_HOST_ACTION_REENABLE;
>  			purge_requests(hostdata, DID_REQUEUE);
>  			wake_up(&hostdata->work_wait_q);
>  		} else {
> @@ -2118,26 +2118,32 @@ static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
>  
>  static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
>  {
> +	unsigned long flags;
>  	int rc;
>  	char *action = "reset";
>  
> -	if (hostdata->reset_crq) {
> -		smp_rmb();
> -		hostdata->reset_crq = 0;
> -
> +	spin_lock_irqsave(hostdata->host->host_lock, flags);
> +	switch (hostdata->action) {
> +	case IBMVSCSI_HOST_ACTION_NONE:
> +		break;
> +	case IBMVSCSI_HOST_ACTION_RESET:
>  		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);

Looks like you are now calling ibmvscsi_reset_crq_queue with the host_lock held.
However, ibmvscsi_reset_crq_queue can call msleep.

This had been implemented as separate reset_crq and reenable_crq fields
so that it could run lockless. I'm not opposed to changing this to a single
field in general, we just need to be careful where we are adding locking.

Thanks,

Brian

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

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template
  2019-05-02  0:47 [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Tyrel Datwyler
  2019-05-02  0:47 ` [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states Tyrel Datwyler
  2019-05-02  0:47 ` [PATCH 3/3] ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON Tyrel Datwyler
@ 2019-05-02 21:50 ` Brian King
  2019-05-03  0:37   ` Tyrel Datwyler
  2 siblings, 1 reply; 7+ messages in thread
From: Brian King @ 2019-05-02 21:50 UTC (permalink / raw)
  To: Tyrel Datwyler, james.bottomley
  Cc: brking, linuxppc-dev, linux-scsi, martin.petersen, Tyrel Datwyler

On 5/1/19 7:47 PM, Tyrel Datwyler wrote:
> From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
> 
> Wire up the host_reset function in our driver_template to allow a user
> requested adpater reset via the host_reset sysfs attribute.
> 
> Example:
> 
> echo "adapter" > /sys/class/scsi_host/host0/host_reset
> 
> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
> ---
>  drivers/scsi/ibmvscsi/ibmvscsi.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 8cec5230fe31..1c37244f16a0 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -2050,6 +2050,18 @@ static struct device_attribute ibmvscsi_host_config = {
>  	.show = show_host_config,
>  };
>  
> +static int ibmvscsi_host_reset(struct Scsi_Host *shost, int reset_type)
> +{
> +	struct ibmvscsi_host_data *hostdata = shost_priv(shost);
> +
> +	vio_disable_interrupts(to_vio_dev(hostdata->dev));
> +	dev_info(hostdata->dev, "Initiating adapter reset!\n");
> +	ibmvscsi_reset_host(hostdata);
> +	vio_enable_interrupts(to_vio_dev(hostdata->dev));

Is it necessary to disable / enable interrupts around the call to ibmvscsi_reset_host?
I don't know why we'd need to do that before calling the reset as we have other
cases, like ibmvscsi_timeout where we don't bother doing this. Also, at the end
of the reset we look to be already enabling interrupts.

Thanks,

Brian

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

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states
  2019-05-02 21:43   ` Brian King
@ 2019-05-03  0:35     ` Tyrel Datwyler
  0 siblings, 0 replies; 7+ messages in thread
From: Tyrel Datwyler @ 2019-05-03  0:35 UTC (permalink / raw)
  To: Brian King, Tyrel Datwyler, james.bottomley
  Cc: brking, linuxppc-dev, linux-scsi, martin.petersen

On 05/02/2019 02:43 PM, Brian King wrote:
> On 5/1/19 7:47 PM, Tyrel Datwyler wrote:
>> From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
>>
>> The current implemenation relies on two flags in the drivers private host
>> structure to signal the need for a host reset or to reenable the CRQ after a
>> LPAR migration. This patch does away with those flags and introduces a single
>> action flag and defined enums for the supported kthread work actions. Lastly,
>> the if/else logic is replaced with a switch statement.
>>
>> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
>> ---
>>  drivers/scsi/ibmvscsi/ibmvscsi.c | 57 +++++++++++++++++++++-----------
>>  drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
>>  2 files changed, 45 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> index 1c37244f16a0..683139e6c63f 100644
>> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
>> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> @@ -828,7 +828,7 @@ static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
>>  	atomic_set(&hostdata->request_limit, 0);
>>  
>>  	purge_requests(hostdata, DID_ERROR);
>> -	hostdata->reset_crq = 1;
>> +	hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
>>  	wake_up(&hostdata->work_wait_q);
>>  }
>>  
>> @@ -1797,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
>>  			/* We need to re-setup the interpartition connection */
>>  			dev_info(hostdata->dev, "Re-enabling adapter!\n");
>>  			hostdata->client_migrated = 1;
>> -			hostdata->reenable_crq = 1;
>> +			hostdata->action = IBMVSCSI_HOST_ACTION_REENABLE;
>>  			purge_requests(hostdata, DID_REQUEUE);
>>  			wake_up(&hostdata->work_wait_q);
>>  		} else {
>> @@ -2118,26 +2118,32 @@ static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
>>  
>>  static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
>>  {
>> +	unsigned long flags;
>>  	int rc;
>>  	char *action = "reset";
>>  
>> -	if (hostdata->reset_crq) {
>> -		smp_rmb();
>> -		hostdata->reset_crq = 0;
>> -
>> +	spin_lock_irqsave(hostdata->host->host_lock, flags);
>> +	switch (hostdata->action) {
>> +	case IBMVSCSI_HOST_ACTION_NONE:
>> +		break;
>> +	case IBMVSCSI_HOST_ACTION_RESET:
>>  		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
> 
> Looks like you are now calling ibmvscsi_reset_crq_queue with the host_lock held.
> However, ibmvscsi_reset_crq_queue can call msleep.

Good catch. I remember thinking that needed to run lockless, but clearly failed
to release and re-grab the lock around that call.

-Tyrel

> 
> This had been implemented as separate reset_crq and reenable_crq fields
> so that it could run lockless. I'm not opposed to changing this to a single
> field in general, we just need to be careful where we are adding locking.
> 
> Thanks,
> 
> Brian
> 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template
  2019-05-02 21:50 ` [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Brian King
@ 2019-05-03  0:37   ` Tyrel Datwyler
  0 siblings, 0 replies; 7+ messages in thread
From: Tyrel Datwyler @ 2019-05-03  0:37 UTC (permalink / raw)
  To: Brian King, Tyrel Datwyler, james.bottomley
  Cc: brking, linuxppc-dev, linux-scsi, martin.petersen

On 05/02/2019 02:50 PM, Brian King wrote:
> On 5/1/19 7:47 PM, Tyrel Datwyler wrote:
>> From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
>>
>> Wire up the host_reset function in our driver_template to allow a user
>> requested adpater reset via the host_reset sysfs attribute.
>>
>> Example:
>>
>> echo "adapter" > /sys/class/scsi_host/host0/host_reset
>>
>> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
>> ---
>>  drivers/scsi/ibmvscsi/ibmvscsi.c | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> index 8cec5230fe31..1c37244f16a0 100644
>> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
>> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> @@ -2050,6 +2050,18 @@ static struct device_attribute ibmvscsi_host_config = {
>>  	.show = show_host_config,
>>  };
>>  
>> +static int ibmvscsi_host_reset(struct Scsi_Host *shost, int reset_type)
>> +{
>> +	struct ibmvscsi_host_data *hostdata = shost_priv(shost);
>> +
>> +	vio_disable_interrupts(to_vio_dev(hostdata->dev));
>> +	dev_info(hostdata->dev, "Initiating adapter reset!\n");
>> +	ibmvscsi_reset_host(hostdata);
>> +	vio_enable_interrupts(to_vio_dev(hostdata->dev));
> 
> Is it necessary to disable / enable interrupts around the call to ibmvscsi_reset_host?
> I don't know why we'd need to do that before calling the reset as we have other
> cases, like ibmvscsi_timeout where we don't bother doing this. Also, at the end
> of the reset we look to be already enabling interrupts.

Yeah, I think you are right. My initial line of thought was that we have
interrupts disabled in handle_crq when we do a reset, but yeah we clearly call
it in the case of a timeout with them enabled.

-Tyrel

> 
> Thanks,
> 
> Brian
> 

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-05-03  0:37 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-02  0:47 [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Tyrel Datwyler
2019-05-02  0:47 ` [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states Tyrel Datwyler
2019-05-02 21:43   ` Brian King
2019-05-03  0:35     ` Tyrel Datwyler
2019-05-02  0:47 ` [PATCH 3/3] ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON Tyrel Datwyler
2019-05-02 21:50 ` [PATCH 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template Brian King
2019-05-03  0:37   ` Tyrel Datwyler

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