isci: filter broadcast change notifications during SMP phy resets

When resetting a sata device in the domain we have seen occasions where
libsas prematurely marks a device gone in the time it takes for the
device to re-establish the link.  This plays badly with software raid
arrays.  Other libsas drivers have non-uniform delays in their reset
handlers to try to cover this condition, but not sufficient to close the
hole.  Given that a sata device can take many seconds to recover we
filter bcns and poll for the device reattach state before notifying
libsas that the port needs the domain to be rediscovered.  Once this has
been proven out at the lldd level we can think about uplevelling this
feature to a common implementation in libsas.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
[ use kzalloc instead of kmem_cache ]
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
[ use eventq and time macros ]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 258 insertions, 1 deletions

diff --git a/drivers/scsi/isci/task.c b/drivers/scsi/isci/task.c
index 69f17b98e4f..709c0817174 100644
--- a/drivers/scsi/isci/task.c
+++ b/drivers/scsi/isci/task.c
@@ -56,6 +56,7 @@
 #include <linux/completion.h>
 #include <linux/irqflags.h>
 #include "sas.h"
+#include <scsi/libsas.h>
 #include "remote_device.h"
 #include "remote_node_context.h"
 #include "isci.h"
@@ -1397,11 +1398,250 @@ isci_task_request_complete(struct isci_host *ihost,
 	complete(tmf_complete);
 }
 
+static void isci_smp_task_timedout(unsigned long _task)
+{
+	struct sas_task *task = (void *) _task;
+	unsigned long flags;
+
+	spin_lock_irqsave(&task->task_state_lock, flags);
+	if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
+		task->task_state_flags |= SAS_TASK_STATE_ABORTED;
+	spin_unlock_irqrestore(&task->task_state_lock, flags);
+
+	complete(&task->completion);
+}
+
+static void isci_smp_task_done(struct sas_task *task)
+{
+	if (!del_timer(&task->timer))
+		return;
+	complete(&task->completion);
+}
+
+static struct sas_task *isci_alloc_task(void)
+{
+	struct sas_task *task = kzalloc(sizeof(*task), GFP_KERNEL);
+
+	if (task) {
+		INIT_LIST_HEAD(&task->list);
+		spin_lock_init(&task->task_state_lock);
+		task->task_state_flags = SAS_TASK_STATE_PENDING;
+		init_timer(&task->timer);
+		init_completion(&task->completion);
+	}
+
+	return task;
+}
+
+static void isci_free_task(struct isci_host *ihost, struct sas_task  *task)
+{
+	if (task) {
+		BUG_ON(!list_empty(&task->list));
+		kfree(task);
+	}
+}
+
+static int isci_smp_execute_task(struct isci_host *ihost,
+				 struct domain_device *dev, void *req,
+				 int req_size, void *resp, int resp_size)
+{
+	int res, retry;
+	struct sas_task *task = NULL;
+
+	for (retry = 0; retry < 3; retry++) {
+		task = isci_alloc_task();
+		if (!task)
+			return -ENOMEM;
+
+		task->dev = dev;
+		task->task_proto = dev->tproto;
+		sg_init_one(&task->smp_task.smp_req, req, req_size);
+		sg_init_one(&task->smp_task.smp_resp, resp, resp_size);
+
+		task->task_done = isci_smp_task_done;
+
+		task->timer.data = (unsigned long) task;
+		task->timer.function = isci_smp_task_timedout;
+		task->timer.expires = jiffies + 10*HZ;
+		add_timer(&task->timer);
+
+		res = isci_task_execute_task(task, 1, GFP_KERNEL);
+
+		if (res) {
+			del_timer(&task->timer);
+			dev_err(&ihost->pdev->dev,
+				"%s: executing SMP task failed:%d\n",
+				__func__, res);
+			goto ex_err;
+		}
+
+		wait_for_completion(&task->completion);
+		res = -ECOMM;
+		if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
+			dev_err(&ihost->pdev->dev,
+				"%s: smp task timed out or aborted\n",
+				__func__);
+			isci_task_abort_task(task);
+			if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
+				dev_err(&ihost->pdev->dev,
+					"%s: SMP task aborted and not done\n",
+					__func__);
+				goto ex_err;
+			}
+		}
+		if (task->task_status.resp == SAS_TASK_COMPLETE &&
+		    task->task_status.stat == SAM_STAT_GOOD) {
+			res = 0;
+			break;
+		}
+		if (task->task_status.resp == SAS_TASK_COMPLETE &&
+		      task->task_status.stat == SAS_DATA_UNDERRUN) {
+			/* no error, but return the number of bytes of
+			* underrun */
+			res = task->task_status.residual;
+			break;
+		}
+		if (task->task_status.resp == SAS_TASK_COMPLETE &&
+		      task->task_status.stat == SAS_DATA_OVERRUN) {
+			res = -EMSGSIZE;
+			break;
+		} else {
+			dev_err(&ihost->pdev->dev,
+				"%s: task to dev %016llx response: 0x%x "
+				"status 0x%x\n", __func__,
+				SAS_ADDR(dev->sas_addr),
+				task->task_status.resp,
+				task->task_status.stat);
+			isci_free_task(ihost, task);
+			task = NULL;
+		}
+	}
+ex_err:
+	BUG_ON(retry == 3 && task != NULL);
+	isci_free_task(ihost, task);
+	return res;
+}
+
+#define DISCOVER_REQ_SIZE  16
+#define DISCOVER_RESP_SIZE 56
+
+int isci_smp_get_phy_attached_dev_type(struct isci_host *ihost,
+				       struct domain_device *dev,
+				       int phy_id, int *adt)
+{
+	struct smp_resp *disc_resp;
+	u8 *disc_req;
+	int res;
+
+	disc_resp = kzalloc(DISCOVER_RESP_SIZE, GFP_KERNEL);
+	if (!disc_resp)
+		return -ENOMEM;
+
+	disc_req = kzalloc(DISCOVER_REQ_SIZE, GFP_KERNEL);
+	if (disc_req) {
+		disc_req[0] = SMP_REQUEST;
+		disc_req[1] = SMP_DISCOVER;
+		disc_req[9] = phy_id;
+	} else {
+		kfree(disc_resp);
+		return -ENOMEM;
+	}
+	res = isci_smp_execute_task(ihost, dev, disc_req, DISCOVER_REQ_SIZE,
+				    disc_resp, DISCOVER_RESP_SIZE);
+	if (!res) {
+		if (disc_resp->result != SMP_RESP_FUNC_ACC)
+			res = disc_resp->result;
+		else
+			*adt = disc_resp->disc.attached_dev_type;
+	}
+	kfree(disc_req);
+	kfree(disc_resp);
+
+	return res;
+}
+
+static void isci_wait_for_smp_phy_reset(struct isci_remote_device *idev, int phy_num)
+{
+	struct domain_device *dev = idev->domain_dev;
+	struct isci_port *iport = idev->isci_port;
+	struct isci_host *ihost = iport->isci_host;
+	int res, iteration = 0, attached_device_type;
+	#define STP_WAIT_MSECS 25000
+	unsigned long tmo = msecs_to_jiffies(STP_WAIT_MSECS);
+	unsigned long deadline = jiffies + tmo;
+	enum {
+		SMP_PHYWAIT_PHYDOWN,
+		SMP_PHYWAIT_PHYUP,
+		SMP_PHYWAIT_DONE
+	} phy_state = SMP_PHYWAIT_PHYDOWN;
+
+	/* While there is time, wait for the phy to go away and come back */
+	while (time_is_after_jiffies(deadline) && phy_state != SMP_PHYWAIT_DONE) {
+		int event = atomic_read(&iport->event);
+
+		++iteration;
+
+		tmo = wait_event_timeout(ihost->eventq,
+					 event != atomic_read(&iport->event) ||
+					 !test_bit(IPORT_BCN_BLOCKED, &iport->flags),
+					 tmo);
+		/* link down, stop polling */
+		if (!test_bit(IPORT_BCN_BLOCKED, &iport->flags))
+			break;
+
+		dev_dbg(&ihost->pdev->dev,
+			"%s: iport %p, iteration %d,"
+			" phase %d: time_remaining %lu, bcns = %d\n",
+			__func__, iport, iteration, phy_state,
+			tmo, test_bit(IPORT_BCN_PENDING, &iport->flags));
+
+		res = isci_smp_get_phy_attached_dev_type(ihost, dev, phy_num,
+							 &attached_device_type);
+		tmo = deadline - jiffies;
+
+		if (res) {
+			dev_warn(&ihost->pdev->dev,
+				 "%s: iteration %d, phase %d:"
+				 " SMP error=%d, time_remaining=%lu\n",
+				 __func__, iteration, phy_state, res, tmo);
+			break;
+		}
+		dev_dbg(&ihost->pdev->dev,
+			"%s: iport %p, iteration %d,"
+			" phase %d: time_remaining %lu, bcns = %d, "
+			"attdevtype = %x\n",
+			__func__, iport, iteration, phy_state,
+			tmo, test_bit(IPORT_BCN_PENDING, &iport->flags),
+			attached_device_type);
+
+		switch (phy_state) {
+		case SMP_PHYWAIT_PHYDOWN:
+			/* Has the device gone away? */
+			if (!attached_device_type)
+				phy_state = SMP_PHYWAIT_PHYUP;
+
+			break;
+
+		case SMP_PHYWAIT_PHYUP:
+			/* Has the device come back? */
+			if (attached_device_type)
+				phy_state = SMP_PHYWAIT_DONE;
+			break;
+
+		case SMP_PHYWAIT_DONE:
+			break;
+		}
+
+	}
+	dev_dbg(&ihost->pdev->dev, "%s: done\n",  __func__);
+}
+
 static int isci_reset_device(struct domain_device *dev, int hard_reset)
 {
 	struct isci_remote_device *idev = dev->lldd_dev;
 	struct sas_phy *phy = sas_find_local_phy(dev);
 	struct isci_host *ihost = dev_to_ihost(dev);
+	struct isci_port *iport = idev->isci_port;
 	enum sci_status status;
 	unsigned long flags;
 	int rc;
@@ -1432,6 +1672,10 @@ static int isci_reset_device(struct domain_device *dev, int hard_reset)
 	/* Make sure all pending requests are able to be fully terminated. */
 	isci_device_clear_reset_pending(ihost, idev);
 
+	/* If this is a device on an expander, disable BCN processing. */
+	if (!scsi_is_sas_phy_local(phy))
+		set_bit(IPORT_BCN_BLOCKED, &iport->flags);
+
 	rc = sas_phy_reset(phy, hard_reset);
 
 	/* Terminate in-progress I/O now. */
@@ -1442,7 +1686,20 @@ static int isci_reset_device(struct domain_device *dev, int hard_reset)
 	status = scic_remote_device_reset_complete(&idev->sci);
 	spin_unlock_irqrestore(&ihost->scic_lock, flags);
 
-	msleep(2000); /* just like mvsas */
+	/* If this is a device on an expander, bring the phy back up. */
+	if (!scsi_is_sas_phy_local(phy)) {
+		/* A phy reset will cause the device to go away then reappear.
+		 * Since libsas will take action on incoming BCNs (eg. remove
+		 * a device going through an SMP phy-control driven reset),
+		 * we need to wait until the phy comes back up before letting
+		 * discovery proceed in libsas.
+		 */
+		isci_wait_for_smp_phy_reset(idev, phy->number);
+
+		spin_lock_irqsave(&ihost->scic_lock, flags);
+		isci_port_bcn_enable(ihost, idev->isci_port);
+		spin_unlock_irqrestore(&ihost->scic_lock, flags);
+	}
 
 	if (status != SCI_SUCCESS) {
 		dev_warn(&ihost->pdev->dev,