isci: replace isci_timer list with proper embedded timers

Rather than preallocating a list of timers and doling them out at runtime,
embed a struct timerlist in each object that needs one.  A struct sci_timer
interface is introduced to manage the timer cancellation semantics which
currently need to guarantee the timer is cancelled while holding
spin_lock(ihost->scic_lock).  Since the timeout functions also need to acquire
the lock it currently prevents the driver from using del_timer_sync() for
runtime cancellations.

del_timer_sync() is used however before the objects go out of scope.

Signed-off-by: Edmund Nadolski <edmund.nadolski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

4 files changed, 60 insertions, 25 deletions

diff --git a/drivers/scsi/isci/host.c b/drivers/scsi/isci/host.c
index 6cd7648197e..a3269b6fa22 100644
--- a/drivers/scsi/isci/host.c
+++ b/drivers/scsi/isci/host.c
@@ -1359,6 +1359,13 @@ void isci_host_deinit(struct isci_host *ihost)
 
 	wait_for_stop(ihost);
 	scic_controller_reset(&ihost->sci);
+
+	/* Cancel any/all outstanding port timers */
+	for (i = 0; i < ihost->sci.logical_port_entries; i++) {
+		struct scic_sds_port *sci_port = &ihost->ports[i].sci;
+		del_timer_sync(&sci_port->timer.timer);
+	}
+
 	isci_timer_list_destroy(ihost);
 }
 
diff --git a/drivers/scsi/isci/isci.h b/drivers/scsi/isci/isci.h
index 69826eac97b..2fe5557d859 100644
--- a/drivers/scsi/isci/isci.h
+++ b/drivers/scsi/isci/isci.h
@@ -551,4 +551,37 @@ extern unsigned char max_concurr_spinup;
 irqreturn_t isci_msix_isr(int vec, void *data);
 irqreturn_t isci_intx_isr(int vec, void *data);
 irqreturn_t isci_error_isr(int vec, void *data);
+
+/*
+ * Each timer is associated with a cancellation flag that is set when
+ * del_timer() is called and checked in the timer callback function. This
+ * is needed since del_timer_sync() cannot be called with scic_lock held.
+ * For deinit however, del_timer_sync() is used without holding the lock.
+ */
+struct sci_timer {
+	struct timer_list	timer;
+	bool			cancel;
+};
+
+static inline
+void sci_init_timer(struct sci_timer *tmr, void (*fn)(unsigned long))
+{
+	tmr->timer.function = fn;
+	tmr->timer.data = (unsigned long) tmr;
+	tmr->cancel = 0;
+	init_timer(&tmr->timer);
+}
+
+static inline void sci_mod_timer(struct sci_timer *tmr, unsigned long msec)
+{
+	tmr->cancel = 0;
+	mod_timer(&tmr->timer, jiffies + msecs_to_jiffies(msec));
+}
+
+static inline void sci_del_timer(struct sci_timer *tmr)
+{
+	tmr->cancel = 1;
+	del_timer(&tmr->timer);
+}
+
 #endif  /* __ISCI_H__ */
diff --git a/drivers/scsi/isci/port.c b/drivers/scsi/isci/port.c
index 3050415e228..3da9048b45b 100644
--- a/drivers/scsi/isci/port.c
+++ b/drivers/scsi/isci/port.c
@@ -926,17 +926,19 @@ bool scic_sds_port_link_detected(
 	return true;
 }
 
-/**
- * This method is provided to timeout requests for port operations. Mostly its
- *    for the port reset operation.
- *
- *
- */
-static void scic_sds_port_timeout_handler(void *port)
+static void port_timeout(unsigned long data)
 {
-	struct scic_sds_port *sci_port = port;
+	struct sci_timer *tmr = (struct sci_timer *)data;
+	struct scic_sds_port *sci_port = container_of(tmr, typeof(*sci_port), timer);
+	struct isci_host *ihost = scic_to_ihost(sci_port->owning_controller);
+	unsigned long flags;
 	u32 current_state;
 
+	spin_lock_irqsave(&ihost->scic_lock, flags);
+
+	if (tmr->cancel)
+		goto done;
+
 	current_state = sci_base_state_machine_get_state(&sci_port->state_machine);
 
 	if (current_state == SCI_BASE_PORT_STATE_RESETTING) {
@@ -965,6 +967,9 @@ static void scic_sds_port_timeout_handler(void *port)
 			"%s: SCIC Port 0x%p is processing a timeout operation "
 			"in state %d.\n", __func__, sci_port, current_state);
 	}
+
+done:
+	spin_unlock_irqrestore(&ihost->scic_lock, flags);
 }
 
 /* --------------------------------------------------------------------------- */
@@ -1259,7 +1264,6 @@ static void scic_sds_port_ready_substate_configuring_exit(struct sci_base_state_
 enum sci_status scic_sds_port_start(struct scic_sds_port *sci_port)
 {
 	struct scic_sds_controller *scic = sci_port->owning_controller;
-	struct isci_host *ihost = scic_to_ihost(scic);
 	enum sci_status status = SCI_SUCCESS;
 	enum scic_sds_port_states state;
 	u32 phy_mask;
@@ -1280,14 +1284,6 @@ enum sci_status scic_sds_port_start(struct scic_sds_port *sci_port)
 		return SCI_FAILURE_UNSUPPORTED_PORT_CONFIGURATION;
 	}
 
-	sci_port->timer_handle =
-		isci_timer_create(ihost,
-				  sci_port,
-				  scic_sds_port_timeout_handler);
-
-	if (!sci_port->timer_handle)
-		return SCI_FAILURE_INSUFFICIENT_RESOURCES;
-
 	if (sci_port->reserved_rni == SCU_DUMMY_INDEX) {
 		u16 rni = scic_sds_remote_node_table_allocate_remote_node(
 				&scic->available_remote_nodes, 1);
@@ -1390,7 +1386,7 @@ static enum sci_status scic_port_hard_reset(struct scic_sds_port *sci_port, u32
 	if (status != SCI_SUCCESS)
 		return status;
 
-	isci_timer_start(sci_port->timer_handle, timeout);
+	sci_mod_timer(&sci_port->timer, timeout);
 	sci_port->not_ready_reason = SCIC_PORT_NOT_READY_HARD_RESET_REQUESTED;
 
 	port_state_machine_change(sci_port,
@@ -1757,14 +1753,14 @@ static void scic_sds_port_resetting_state_exit(struct sci_base_state_machine *sm
 {
 	struct scic_sds_port *sci_port = container_of(sm, typeof(*sci_port), state_machine);
 
-	isci_timer_stop(sci_port->timer_handle);
+	sci_del_timer(&sci_port->timer);
 }
 
 static void scic_sds_port_stopping_state_exit(struct sci_base_state_machine *sm)
 {
 	struct scic_sds_port *sci_port = container_of(sm, typeof(*sci_port), state_machine);
 
-	isci_timer_stop(sci_port->timer_handle);
+	sci_del_timer(&sci_port->timer);
 
 	scic_sds_port_destroy_dummy_resources(sci_port);
 }
@@ -1831,7 +1827,8 @@ void scic_sds_port_construct(struct scic_sds_port *sci_port, u8 index,
 	sci_port->reserved_rni = SCU_DUMMY_INDEX;
 	sci_port->reserved_tci = SCU_DUMMY_INDEX;
 
-	sci_port->timer_handle = NULL;
+	sci_init_timer(&sci_port->timer, port_timeout);
+
 	sci_port->port_task_scheduler_registers = NULL;
 
 	for (index = 0; index < SCI_MAX_PHYS; index++)
diff --git a/drivers/scsi/isci/port.h b/drivers/scsi/isci/port.h
index af540e5c03a..9a6912855fc 100644
--- a/drivers/scsi/isci/port.h
+++ b/drivers/scsi/isci/port.h
@@ -139,10 +139,8 @@ struct scic_sds_port {
 	 */
 	struct scic_sds_controller *owning_controller;
 
-	/**
-	 * This field contains the port start/stop timer handle.
-	 */
-	void *timer_handle;
+	/* timer used for port start/stop operations */
+	struct sci_timer	timer;
 
 	/**
 	 * This field is the pointer to the port task scheduler registers