isci: unify can_queue tracking on the tci_pool, uplevel tag assignment

The tci_pool tracks our outstanding command slots which are also the 'index'
portion of our tags.  Grabbing the tag early in ->lldd_execute_task let's us
drop the isci_host_can_queue() and ->was_tag_assigned_by_user infrastructure.
->was_tag_assigned_by_user required the task context to be duplicated in
request-local buffer.  With the tci established early we can build the
task_context directly into its final location and skip a memcpy.

With the task context buffer at a known address at request construction we
have the opportunity/obligation to also fix sgl handling.  This rework feels
like it belongs in another patch but the sgl handling and task_context are too
intertwined.
1/ fix the 'ab' pair embedded in the task context to point to the 'cd' pair in
   the task context (previously we were prematurely linking to the staging
   buffer).
2/ fix the broken iteration of pio sgls that assumes all sgls are relative to
   the request, and does a dangerous looking reverse lookup of physical
   address to virtual address.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/host.h

@@ -192,6 +192,7 @@ struct scic_sds_controller {
 	 * context table.  This data is shared between the hardware and software.
 	 */
 	struct scu_task_context *task_context_table;
+	dma_addr_t task_context_dma;
 
 	/**
 	 * This field is a pointer to the memory allocated by the driver for the
@@ -302,12 +303,8 @@ struct isci_host {
 	struct isci_port ports[SCI_MAX_PORTS + 1]; /* includes dummy port */
 	struct sas_ha_struct sas_ha;
 
-	int can_queue;
-	spinlock_t queue_lock;
 	spinlock_t state_lock;
-
 	struct pci_dev *pdev;
-
 	enum isci_status status;
 	#define IHOST_START_PENDING 0
 	#define IHOST_STOP_PENDING 1
@@ -451,36 +448,6 @@ static inline void isci_host_change_state(struct isci_host *isci_host,
 
 }
 
-static inline int isci_host_can_queue(struct isci_host *isci_host, int num)
-{
-	int ret = 0;
-	unsigned long flags;
-
-	spin_lock_irqsave(&isci_host->queue_lock, flags);
-	if ((isci_host->can_queue - num) < 0) {
-		dev_dbg(&isci_host->pdev->dev,
-			"%s: isci_host->can_queue = %d\n",
-			__func__,
-			isci_host->can_queue);
-		ret = -SAS_QUEUE_FULL;
-
-	} else
-		isci_host->can_queue -= num;
-
-	spin_unlock_irqrestore(&isci_host->queue_lock, flags);
-
-	return ret;
-}
-
-static inline void isci_host_can_dequeue(struct isci_host *isci_host, int num)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&isci_host->queue_lock, flags);
-	isci_host->can_queue += num;
-	spin_unlock_irqrestore(&isci_host->queue_lock, flags);
-}
-
 static inline void wait_for_start(struct isci_host *ihost)
 {
 	wait_event(ihost->eventq, !test_bit(IHOST_START_PENDING, &ihost->flags));
@@ -646,10 +613,6 @@ union scu_remote_node_context *scic_sds_controller_get_remote_node_context_buffe
 struct scic_sds_request *scic_request_by_tag(struct scic_sds_controller *scic,
 					     u16 io_tag);
 
-struct scu_task_context *scic_sds_controller_get_task_context_buffer(
-	struct scic_sds_controller *scic,
-	u16 io_tag);
-
 void scic_sds_controller_power_control_queue_insert(
 	struct scic_sds_controller *scic,
 	struct scic_sds_phy *sci_phy);
@@ -681,6 +644,9 @@ void scic_sds_controller_register_setup(struct scic_sds_controller *scic);
 enum sci_status scic_controller_continue_io(struct scic_sds_request *sci_req);
 int isci_host_scan_finished(struct Scsi_Host *, unsigned long);
 void isci_host_scan_start(struct Scsi_Host *);
+u16 isci_alloc_tag(struct isci_host *ihost);
+enum sci_status isci_free_tag(struct isci_host *ihost, u16 io_tag);
+void isci_tci_free(struct isci_host *ihost, u16 tci);
 
 int isci_host_init(struct isci_host *);
 
@@ -708,14 +674,12 @@ void scic_controller_disable_interrupts(
 enum sci_status scic_controller_start_io(
 	struct scic_sds_controller *scic,
 	struct scic_sds_remote_device *remote_device,
-	struct scic_sds_request *io_request,
-	u16 io_tag);
+	struct scic_sds_request *io_request);
 
 enum sci_task_status scic_controller_start_task(
 	struct scic_sds_controller *scic,
 	struct scic_sds_remote_device *remote_device,
-	struct scic_sds_request *task_request,
-	u16 io_tag);
+	struct scic_sds_request *task_request);
 
 enum sci_status scic_controller_terminate_request(
 	struct scic_sds_controller *scic,
@@ -727,13 +691,6 @@ enum sci_status scic_controller_complete_io(
 	struct scic_sds_remote_device *remote_device,
 	struct scic_sds_request *io_request);
 
-u16 scic_controller_allocate_io_tag(
-	struct scic_sds_controller *scic);
-
-enum sci_status scic_controller_free_io_tag(
-	struct scic_sds_controller *scic,
-	u16 io_tag);
-
 void scic_sds_port_configuration_agent_construct(
 	struct scic_sds_port_configuration_agent *port_agent);
 

drivers/scsi/isci/port.c

@@ -695,35 +695,21 @@ static void scic_sds_port_construct_dummy_rnc(struct scic_sds_port *sci_port, u1
  */
 static void scic_sds_port_construct_dummy_task(struct scic_sds_port *sci_port, u16 tag)
 {
+	struct scic_sds_controller *scic = sci_port->owning_controller;
 	struct scu_task_context *task_context;
 
-	task_context = scic_sds_controller_get_task_context_buffer(sci_port->owning_controller, tag);
-
+	task_context = &scic->task_context_table[ISCI_TAG_TCI(tag)];
 	memset(task_context, 0, sizeof(struct scu_task_context));
 
-	task_context->abort = 0;
-	task_context->priority = 0;
 	task_context->initiator_request = 1;
 	task_context->connection_rate = 1;
-	task_context->protocol_engine_index = 0;
 	task_context->logical_port_index = sci_port->physical_port_index;
 	task_context->protocol_type = SCU_TASK_CONTEXT_PROTOCOL_SSP;
 	task_context->task_index = ISCI_TAG_TCI(tag);
 	task_context->valid = SCU_TASK_CONTEXT_VALID;
 	task_context->context_type = SCU_TASK_CONTEXT_TYPE;
-
 	task_context->remote_node_index = sci_port->reserved_rni;
-	task_context->command_code = 0;
-
-	task_context->link_layer_control = 0;
 	task_context->do_not_dma_ssp_good_response = 1;
-	task_context->strict_ordering = 0;
-	task_context->control_frame = 0;
-	task_context->timeout_enable = 0;
-	task_context->block_guard_enable = 0;
-
-	task_context->address_modifier = 0;
-
 	task_context->task_phase = 0x01;
 }
 
@@ -731,15 +717,15 @@ static void scic_sds_port_destroy_dummy_resources(struct scic_sds_port *sci_port
 {
 	struct scic_sds_controller *scic = sci_port->owning_controller;
 
-	if (sci_port->reserved_tci != SCU_DUMMY_INDEX)
-		scic_controller_free_io_tag(scic, sci_port->reserved_tci);
+	if (sci_port->reserved_tag != SCI_CONTROLLER_INVALID_IO_TAG)
+		isci_free_tag(scic_to_ihost(scic), sci_port->reserved_tag);
 
 	if (sci_port->reserved_rni != SCU_DUMMY_INDEX)
 		scic_sds_remote_node_table_release_remote_node_index(&scic->available_remote_nodes,
 								     1, sci_port->reserved_rni);
 
 	sci_port->reserved_rni = SCU_DUMMY_INDEX;
-	sci_port->reserved_tci = SCU_DUMMY_INDEX;
+	sci_port->reserved_tag = SCI_CONTROLLER_INVALID_IO_TAG;
 }
 
 /**
@@ -1119,18 +1105,17 @@ scic_sds_port_suspend_port_task_scheduler(struct scic_sds_port *port)
  */
 static void scic_sds_port_post_dummy_request(struct scic_sds_port *sci_port)
 {
-	u32 command;
-	struct scu_task_context *task_context;
 	struct scic_sds_controller *scic = sci_port->owning_controller;
-	u16 tci = sci_port->reserved_tci;
-
-	task_context = scic_sds_controller_get_task_context_buffer(scic, tci);
+	u16 tag = sci_port->reserved_tag;
+	struct scu_task_context *tc;
+	u32 command;
 
-	task_context->abort = 0;
+	tc = &scic->task_context_table[ISCI_TAG_TCI(tag)];
+	tc->abort = 0;
 
 	command = SCU_CONTEXT_COMMAND_REQUEST_TYPE_POST_TC |
 		  sci_port->physical_port_index << SCU_CONTEXT_COMMAND_LOGICAL_PORT_SHIFT |
-		  tci;
+		  ISCI_TAG_TCI(tag);
 
 	scic_sds_controller_post_request(scic, command);
 }
@@ -1145,17 +1130,16 @@ static void scic_sds_port_post_dummy_request(struct scic_sds_port *sci_port)
 static void scic_sds_port_abort_dummy_request(struct scic_sds_port *sci_port)
 {
 	struct scic_sds_controller *scic = sci_port->owning_controller;
-	u16 tci = sci_port->reserved_tci;
+	u16 tag = sci_port->reserved_tag;
 	struct scu_task_context *tc;
 	u32 command;
 
-	tc = scic_sds_controller_get_task_context_buffer(scic, tci);
-
+	tc = &scic->task_context_table[ISCI_TAG_TCI(tag)];
 	tc->abort = 1;
 
 	command = SCU_CONTEXT_COMMAND_REQUEST_POST_TC_ABORT |
 		  sci_port->physical_port_index << SCU_CONTEXT_COMMAND_LOGICAL_PORT_SHIFT |
-		  tci;
+		  ISCI_TAG_TCI(tag);
 
 	scic_sds_controller_post_request(scic, command);
 }
@@ -1333,15 +1317,16 @@ enum sci_status scic_sds_port_start(struct scic_sds_port *sci_port)
 		sci_port->reserved_rni = rni;
 	}
 
-	if (sci_port->reserved_tci == SCU_DUMMY_INDEX) {
-		/* Allocate a TCI and remove the sequence nibble */
-		u16 tci = scic_controller_allocate_io_tag(scic);
+	if (sci_port->reserved_tag == SCI_CONTROLLER_INVALID_IO_TAG) {
+		struct isci_host *ihost = scic_to_ihost(scic);
+		u16 tag;
 
-		if (tci != SCU_DUMMY_INDEX)
-			scic_sds_port_construct_dummy_task(sci_port, tci);
-		else
+		tag = isci_alloc_tag(ihost);
+		if (tag == SCI_CONTROLLER_INVALID_IO_TAG)
 			status = SCI_FAILURE_INSUFFICIENT_RESOURCES;
-		sci_port->reserved_tci = tci;
+		else
+			scic_sds_port_construct_dummy_task(sci_port, tag);
+		sci_port->reserved_tag = tag;
 	}
 
 	if (status == SCI_SUCCESS) {
@@ -1859,7 +1844,7 @@ void scic_sds_port_construct(struct scic_sds_port *sci_port, u8 index,
 	sci_port->assigned_device_count = 0;
 
 	sci_port->reserved_rni = SCU_DUMMY_INDEX;
-	sci_port->reserved_tci = SCU_DUMMY_INDEX;
+	sci_port->reserved_tag = SCI_CONTROLLER_INVALID_IO_TAG;
 
 	sci_init_timer(&sci_port->timer, port_timeout);
 

drivers/scsi/isci/port.h

@@ -108,7 +108,7 @@ struct scic_sds_port {
 	u8 active_phy_mask;
 
 	u16 reserved_rni;
-	u16 reserved_tci;
+	u16 reserved_tag;
 
 	/**
 	 * This field contains the count of the io requests started on this port

drivers/scsi/isci/request.h

@@ -136,7 +136,7 @@ struct scic_sds_stp_request {
 			u8 ending_error;
 
 			struct scic_sds_request_pio_sgl {
-				struct scu_sgl_element_pair *sgl_pair;
+				int sgl_index;
 				u8 sgl_set;
 				u32 sgl_offset;
 			} request_current;
@@ -171,12 +171,6 @@ struct scic_sds_request {
 	 */
 	struct scic_sds_remote_device *target_device;
 
-	/*
-	 * This field is utilized to determine if the SCI user is managing
-	 * the IO tag for this request or if the core is managing it.
-	 */
-	bool was_tag_assigned_by_user;
-
 	/*
 	 * This field indicates the IO tag for this request.  The IO tag is
 	 * comprised of the task_index and a sequence count. The sequence count
@@ -209,8 +203,7 @@ struct scic_sds_request {
 	 */
 	u32 post_context;
 
-	struct scu_task_context *task_context_buffer;
-	struct scu_task_context tc ____cacheline_aligned;
+	struct scu_task_context *tc;
 
 	/* could be larger with sg chaining */
 	#define SCU_SGL_SIZE ((SCI_MAX_SCATTER_GATHER_ELEMENTS + 1) / 2)
@@ -465,35 +458,6 @@ enum sci_base_request_states {
 		(request)->sci_status = (sci_status_code); \
 	}
 
-/**
- * SCU_SGL_ZERO() -
- *
- * This macro zeros the hardware SGL element data
- */
-#define SCU_SGL_ZERO(scu_sge) \
-	{ \
-		(scu_sge).length = 0; \
-		(scu_sge).address_lower = 0; \
-		(scu_sge).address_upper = 0; \
-		(scu_sge).address_modifier = 0;	\
-	}
-
-/**
- * SCU_SGL_COPY() -
- *
- * This macro copys the SGL Element data from the host os to the hardware SGL
- * elment data
- */
-#define SCU_SGL_COPY(scu_sge, os_sge) \
-	{ \
-		(scu_sge).length = sg_dma_len(sg); \
-		(scu_sge).address_upper = \
-			upper_32_bits(sg_dma_address(sg)); \
-		(scu_sge).address_lower = \
-			lower_32_bits(sg_dma_address(sg)); \
-		(scu_sge).address_modifier = 0;	\
-	}
-
 enum sci_status scic_sds_request_start(struct scic_sds_request *sci_req);
 enum sci_status scic_sds_io_request_terminate(struct scic_sds_request *sci_req);
 enum sci_status
@@ -509,22 +473,6 @@ scic_sds_request_complete(struct scic_sds_request *sci_req);
 extern enum sci_status
 scic_sds_io_request_tc_completion(struct scic_sds_request *sci_req, u32 code);
 
-/* XXX open code in caller */
-static inline void *scic_request_get_virt_addr(struct scic_sds_request *sci_req,
-					       dma_addr_t phys_addr)
-{
-	struct isci_request *ireq = sci_req_to_ireq(sci_req);
-	dma_addr_t offset;
-
-	BUG_ON(phys_addr < ireq->request_daddr);
-
-	offset = phys_addr - ireq->request_daddr;
-
-	BUG_ON(offset >= sizeof(*ireq));
-
-	return (char *)ireq + offset;
-}
-
 /* XXX open code in caller */
 static inline dma_addr_t
 scic_io_request_get_dma_addr(struct scic_sds_request *sci_req, void *virt_addr)
@@ -672,7 +620,7 @@ struct isci_request *isci_request_alloc_tmf(struct isci_host *ihost,
 					    struct isci_tmf *isci_tmf,
 					    gfp_t gfp_flags);
 int isci_request_execute(struct isci_host *ihost, struct isci_remote_device *idev,
-			 struct sas_task *task, gfp_t gfp_flags);
+			 struct sas_task *task, u16 tag, gfp_t gfp_flags);
 void isci_terminate_pending_requests(struct isci_host *ihost,
 				     struct isci_remote_device *idev);
 enum sci_status

drivers/scsi/isci/task.c

@@ -63,6 +63,7 @@
 #include "request.h"
 #include "sata.h"
 #include "task.h"
+#include "host.h"
 
 /**
 * isci_task_refuse() - complete the request to the upper layer driver in
@@ -156,25 +157,19 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 {
 	struct isci_host *ihost = dev_to_ihost(task->dev);
 	struct isci_remote_device *idev;
-	enum sci_status status;
 	unsigned long flags;
 	bool io_ready;
-	int ret;
+	u16 tag;
 
 	dev_dbg(&ihost->pdev->dev, "%s: num=%d\n", __func__, num);
 
-	/* Check if we have room for more tasks */
-	ret = isci_host_can_queue(ihost, num);
-
-	if (ret) {
-		dev_warn(&ihost->pdev->dev, "%s: queue full\n", __func__);
-		return ret;
-	}
-
 	for_each_sas_task(num, task) {
+		enum sci_status status = SCI_FAILURE;
+
 		spin_lock_irqsave(&ihost->scic_lock, flags);
 		idev = isci_lookup_device(task->dev);
 		io_ready = isci_device_io_ready(idev, task);
+		tag = isci_alloc_tag(ihost);
 		spin_unlock_irqrestore(&ihost->scic_lock, flags);
 
 		dev_dbg(&ihost->pdev->dev,
@@ -185,15 +180,12 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 		if (!idev) {
 			isci_task_refuse(ihost, task, SAS_TASK_UNDELIVERED,
 					 SAS_DEVICE_UNKNOWN);
-			isci_host_can_dequeue(ihost, 1);
-		} else if (!io_ready) {
-
+		} else if (!io_ready || tag == SCI_CONTROLLER_INVALID_IO_TAG) {
 			/* Indicate QUEUE_FULL so that the scsi midlayer
 			 * retries.
 			  */
 			isci_task_refuse(ihost, task, SAS_TASK_COMPLETE,
 					 SAS_QUEUE_FULL);
-			isci_host_can_dequeue(ihost, 1);
 		} else {
 			/* There is a device and it's ready for I/O. */
 			spin_lock_irqsave(&task->task_state_lock, flags);
@@ -206,13 +198,12 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 				isci_task_refuse(ihost, task,
 						 SAS_TASK_UNDELIVERED,
 						 SAM_STAT_TASK_ABORTED);
-				isci_host_can_dequeue(ihost, 1);
 			} else {
 				task->task_state_flags |= SAS_TASK_AT_INITIATOR;
 				spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 				/* build and send the request. */
-				status = isci_request_execute(ihost, idev, task, gfp_flags);
+				status = isci_request_execute(ihost, idev, task, tag, gfp_flags);
 
 				if (status != SCI_SUCCESS) {
 
@@ -231,10 +222,17 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 					isci_task_refuse(ihost, task,
 							 SAS_TASK_COMPLETE,
 							 SAS_QUEUE_FULL);
-					isci_host_can_dequeue(ihost, 1);
 				}
 			}
 		}
+		if (status != SCI_SUCCESS && tag != SCI_CONTROLLER_INVALID_IO_TAG) {
+			spin_lock_irqsave(&ihost->scic_lock, flags);
+			/* command never hit the device, so just free
+			 * the tci and skip the sequence increment
+			 */
+			isci_tci_free(ihost, ISCI_TAG_TCI(tag));
+			spin_unlock_irqrestore(&ihost->scic_lock, flags);
+		}
 		isci_put_device(idev);
 	}
 	return 0;
@@ -242,7 +240,7 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 
 static struct isci_request *isci_task_request_build(struct isci_host *ihost,
 						    struct isci_remote_device *idev,
-						    struct isci_tmf *isci_tmf)
+						    u16 tag, struct isci_tmf *isci_tmf)
 {
 	enum sci_status status = SCI_FAILURE;
 	struct isci_request *ireq = NULL;
@@ -259,8 +257,7 @@ static struct isci_request *isci_task_request_build(struct isci_host *ihost,
 		return NULL;
 
 	/* let the core do it's construct. */
-	status = scic_task_request_construct(&ihost->sci, &idev->sci,
-					     SCI_CONTROLLER_INVALID_IO_TAG,
+	status = scic_task_request_construct(&ihost->sci, &idev->sci, tag,
 					     &ireq->sci);
 
 	if (status != SCI_SUCCESS) {
@@ -290,8 +287,7 @@ static struct isci_request *isci_task_request_build(struct isci_host *ihost,
 	return ireq;
  errout:
 	isci_request_free(ihost, ireq);
-	ireq = NULL;
-	return ireq;
+	return NULL;
 }
 
 int isci_task_execute_tmf(struct isci_host *ihost,
@@ -305,6 +301,14 @@ int isci_task_execute_tmf(struct isci_host *ihost,
 	int ret = TMF_RESP_FUNC_FAILED;
 	unsigned long flags;
 	unsigned long timeleft;
+	u16 tag;
+
+	spin_lock_irqsave(&ihost->scic_lock, flags);
+	tag = isci_alloc_tag(ihost);
+	spin_unlock_irqrestore(&ihost->scic_lock, flags);
+
+	if (tag == SCI_CONTROLLER_INVALID_IO_TAG)
+		return ret;
 
 	/* sanity check, return TMF_RESP_FUNC_FAILED
 	 * if the device is not there and ready.
@@ -316,7 +320,7 @@ int isci_task_execute_tmf(struct isci_host *ihost,
 			"%s: isci_device = %p not ready (%#lx)\n",
 			__func__,
 			isci_device, isci_device ? isci_device->flags : 0);
-		return TMF_RESP_FUNC_FAILED;
+		goto err_tci;
 	} else
 		dev_dbg(&ihost->pdev->dev,
 			"%s: isci_device = %p\n",
@@ -327,22 +331,16 @@ int isci_task_execute_tmf(struct isci_host *ihost,
 	/* Assign the pointer to the TMF's completion kernel wait structure. */
 	tmf->complete = &completion;
 
-	ireq = isci_task_request_build(ihost, isci_device, tmf);
-	if (!ireq) {
-		dev_warn(&ihost->pdev->dev,
-			"%s: isci_task_request_build failed\n",
-			__func__);
-		return TMF_RESP_FUNC_FAILED;
-	}
+	ireq = isci_task_request_build(ihost, isci_device, tag, tmf);
+	if (!ireq)
+		goto err_tci;
 
 	spin_lock_irqsave(&ihost->scic_lock, flags);
 
 	/* start the TMF io. */
-	status = scic_controller_start_task(
-		&ihost->sci,
-		sci_device,
-		&ireq->sci,
-		SCI_CONTROLLER_INVALID_IO_TAG);
+	status = scic_controller_start_task(&ihost->sci,
+					    sci_device,
+					    &ireq->sci);
 
 	if (status != SCI_TASK_SUCCESS) {
 		dev_warn(&ihost->pdev->dev,
@@ -351,8 +349,7 @@ int isci_task_execute_tmf(struct isci_host *ihost,
 			 status,
 			 ireq);
 		spin_unlock_irqrestore(&ihost->scic_lock, flags);
-		isci_request_free(ihost, ireq);
-		return ret;
+		goto err_ireq;
 	}
 
 	if (tmf->cb_state_func != NULL)
@@ -403,6 +400,15 @@ int isci_task_execute_tmf(struct isci_host *ihost,
 		ireq);
 
 	return ret;
+
+ err_ireq:
+	isci_request_free(ihost, ireq);
+ err_tci:
+	spin_lock_irqsave(&ihost->scic_lock, flags);
+	isci_tci_free(ihost, ISCI_TAG_TCI(tag));
+	spin_unlock_irqrestore(&ihost->scic_lock, flags);
+
+	return ret;
 }
 
 void isci_task_build_tmf(