[PATCH v2 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template

[PATCH v2 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template

[Tyrel Datwyler]

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>
---
Changes in v2:
	removed interrupt disabe/enable around reset

 drivers/scsi/ibmvscsi/ibmvscsi.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 8cec5230fe31..65fc8ca962c5 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -2050,6 +2050,16 @@ 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);
+
+	dev_info(hostdata->dev, "Initiating adapter reset!\n");
+	ibmvscsi_reset_host(hostdata);
+
+	return 0;
+}
+
 static struct device_attribute *ibmvscsi_attrs[] = {
 	&ibmvscsi_host_vhost_loc,
 	&ibmvscsi_host_vhost_name,
@@ -2076,6 +2086,7 @@ 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

[PATCH v2 2/3] ibmvscsi: redo driver work thread to use enum action states

[Tyrel Datwyler]

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>
---
Changes in v2:
	release/grab host_lock around reset/reenable calls

 drivers/scsi/ibmvscsi/ibmvscsi.c | 61 ++++++++++++++++++++++----------
 drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
 2 files changed, 49 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 65fc8ca962c5..8df82c58e7b9 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 {
@@ -2116,48 +2116,71 @@ 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:
+		spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
+		spin_lock_irqsave(hostdata->host->host_lock, flags);
 		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";
+		spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 		rc = ibmvscsi_reenable_crq_queue(&hostdata->queue, hostdata);
-		hostdata->reenable_crq = 0;
+		spin_lock_irqsave(hostdata->host->host_lock, flags);
 		if (!rc)
 			rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
-	} else
-		return;
+		break;
+	default:
+		break;
+	}
+
+	hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
 
 	if (rc) {
 		atomic_set(&hostdata->request_limit, -1);
 		dev_err(hostdata->dev, "error after %s\n", action);
 	}
+	spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 
 	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

[PATCH v2 3/3] ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON

[Tyrel Datwyler]

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>
---
Changes in v2:
	no change

 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 8df82c58e7b9..727c31dc11a0 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);
 }
 
 /**
@@ -2123,6 +2124,7 @@ 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:
 		spin_unlock_irqrestore(hostdata->host->host_lock, flags);
@@ -2164,6 +2166,7 @@ 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

Re: [PATCH v2 1/3] ibmvscsi: Wire up host_reset() in the drivers scsi_host_template

[Martin K. Petersen]

Tyrel,

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

Series applied to 5.3/scsi-queue. Thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering