PCI: pciehp: Handle events synchronously

Up until now, pciehp's IRQ handler schedules a work item for each event,
which in turn schedules a work item to enable or disable the slot.  This
double indirection was necessary because sleeping wasn't allowed in the
IRQ handler.

However it is now that pciehp has been converted to threaded IRQ handling
and polling, so handle events synchronously in pciehp_ist() and remove
the work item infrastructure (with the exception of work items to handle
a button press after the 5 second delay).

For link or presence change events, move the register read to determine
the current link or presence state behind acquisition of the slot lock
to prevent it from becoming stale while the lock is contended.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 55 insertions, 123 deletions

diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index 9d6343a35db1..5763e81be2ed 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -21,24 +21,6 @@
 #include "../pci.h"
 #include "pciehp.h"
 
-static void interrupt_event_handler(struct work_struct *work);
-
-void pciehp_queue_interrupt_event(struct slot *p_slot, u32 event_type)
-{
-	struct event_info *info;
-
-	info = kmalloc(sizeof(*info), GFP_ATOMIC);
-	if (!info) {
-		ctrl_err(p_slot->ctrl, "dropped event %d (ENOMEM)\n", event_type);
-		return;
-	}
-
-	INIT_WORK(&info->work, interrupt_event_handler);
-	info->event_type = event_type;
-	info->p_slot = p_slot;
-	queue_work(p_slot->wq, &info->work);
-}
-
 /* The following routines constitute the bulk of the
    hotplug controller logic
  */
@@ -140,59 +122,6 @@ static void remove_board(struct slot *p_slot)
 	pciehp_green_led_off(p_slot);
 }
 
-struct power_work_info {
-	struct slot *p_slot;
-	struct work_struct work;
-	unsigned int req;
-#define DISABLE_REQ 0
-#define ENABLE_REQ  1
-};
-
-/**
- * pciehp_power_thread - handle pushbutton events
- * @work: &struct work_struct describing work to be done
- *
- * Scheduled procedure to handle blocking stuff for the pushbuttons.
- * Handles all pending events and exits.
- */
-static void pciehp_power_thread(struct work_struct *work)
-{
-	struct power_work_info *info =
-		container_of(work, struct power_work_info, work);
-	struct slot *p_slot = info->p_slot;
-
-	switch (info->req) {
-	case DISABLE_REQ:
-		pciehp_disable_slot(p_slot);
-		break;
-	case ENABLE_REQ:
-		pciehp_enable_slot(p_slot);
-		break;
-	default:
-		break;
-	}
-
-	kfree(info);
-}
-
-static void pciehp_queue_power_work(struct slot *p_slot, int req)
-{
-	struct power_work_info *info;
-
-	p_slot->state = (req == ENABLE_REQ) ? POWERON_STATE : POWEROFF_STATE;
-
-	info = kmalloc(sizeof(*info), GFP_KERNEL);
-	if (!info) {
-		ctrl_err(p_slot->ctrl, "no memory to queue %s request\n",
-			 (req == ENABLE_REQ) ? "poweron" : "poweroff");
-		return;
-	}
-	info->p_slot = p_slot;
-	INIT_WORK(&info->work, pciehp_power_thread);
-	info->req = req;
-	queue_work(p_slot->wq, &info->work);
-}
-
 void pciehp_queue_pushbutton_work(struct work_struct *work)
 {
 	struct slot *p_slot = container_of(work, struct slot, work.work);
@@ -200,25 +129,27 @@ void pciehp_queue_pushbutton_work(struct work_struct *work)
 	mutex_lock(&p_slot->lock);
 	switch (p_slot->state) {
 	case BLINKINGOFF_STATE:
-		pciehp_queue_power_work(p_slot, DISABLE_REQ);
-		break;
+		p_slot->state = POWEROFF_STATE;
+		mutex_unlock(&p_slot->lock);
+		pciehp_disable_slot(p_slot);
+		return;
 	case BLINKINGON_STATE:
-		pciehp_queue_power_work(p_slot, ENABLE_REQ);
-		break;
+		p_slot->state = POWERON_STATE;
+		mutex_unlock(&p_slot->lock);
+		pciehp_enable_slot(p_slot);
+		return;
 	default:
 		break;
 	}
 	mutex_unlock(&p_slot->lock);
 }
 
-/*
- * Note: This function must be called with slot->lock held
- */
-static void handle_button_press_event(struct slot *p_slot)
+void pciehp_handle_button_press(struct slot *p_slot)
 {
 	struct controller *ctrl = p_slot->ctrl;
 	u8 getstatus;
 
+	mutex_lock(&p_slot->lock);
 	switch (p_slot->state) {
 	case STATIC_STATE:
 		pciehp_get_power_status(p_slot, &getstatus);
@@ -269,14 +200,16 @@ static void handle_button_press_event(struct slot *p_slot)
 			 slot_name(p_slot), p_slot->state);
 		break;
 	}
+	mutex_unlock(&p_slot->lock);
 }
 
-/*
- * Note: This function must be called with slot->lock held
- */
-static void handle_link_event(struct slot *p_slot, u32 event)
+void pciehp_handle_link_change(struct slot *p_slot)
 {
 	struct controller *ctrl = p_slot->ctrl;
+	bool link_active;
+
+	mutex_lock(&p_slot->lock);
+	link_active = pciehp_check_link_active(ctrl);
 
 	switch (p_slot->state) {
 	case BLINKINGON_STATE:
@@ -284,24 +217,40 @@ static void handle_link_event(struct slot *p_slot, u32 event)
 		cancel_delayed_work(&p_slot->work);
 		/* Fall through */
 	case STATIC_STATE:
-		pciehp_queue_power_work(p_slot, event == INT_LINK_UP ?
-					ENABLE_REQ : DISABLE_REQ);
+		if (link_active) {
+			p_slot->state = POWERON_STATE;
+			mutex_unlock(&p_slot->lock);
+			ctrl_info(ctrl, "Slot(%s): Link Up\n", slot_name(p_slot));
+			pciehp_enable_slot(p_slot);
+		} else {
+			p_slot->state = POWEROFF_STATE;
+			mutex_unlock(&p_slot->lock);
+			ctrl_info(ctrl, "Slot(%s): Link Down\n", slot_name(p_slot));
+			pciehp_disable_slot(p_slot);
+		}
+		return;
 		break;
 	case POWERON_STATE:
-		if (event == INT_LINK_UP) {
+		if (link_active) {
 			ctrl_info(ctrl, "Slot(%s): Link Up event ignored; already powering on\n",
 				  slot_name(p_slot));
 		} else {
+			p_slot->state = POWEROFF_STATE;
+			mutex_unlock(&p_slot->lock);
 			ctrl_info(ctrl, "Slot(%s): Link Down event queued; currently getting powered on\n",
 				  slot_name(p_slot));
-			pciehp_queue_power_work(p_slot, DISABLE_REQ);
+			pciehp_disable_slot(p_slot);
+			return;
 		}
 		break;
 	case POWEROFF_STATE:
-		if (event == INT_LINK_UP) {
+		if (link_active) {
+			p_slot->state = POWERON_STATE;
+			mutex_unlock(&p_slot->lock);
 			ctrl_info(ctrl, "Slot(%s): Link Up event queued; currently getting powered off\n",
 				  slot_name(p_slot));
-			pciehp_queue_power_work(p_slot, ENABLE_REQ);
+			pciehp_enable_slot(p_slot);
+			return;
 		} else {
 			ctrl_info(ctrl, "Slot(%s): Link Down event ignored; already powering off\n",
 				  slot_name(p_slot));
@@ -312,45 +261,28 @@ static void handle_link_event(struct slot *p_slot, u32 event)
 			 slot_name(p_slot), p_slot->state);
 		break;
 	}
+	mutex_unlock(&p_slot->lock);
 }
 
-static void interrupt_event_handler(struct work_struct *work)
+void pciehp_handle_presence_change(struct slot *slot)
 {
-	struct event_info *info = container_of(work, struct event_info, work);
-	struct slot *p_slot = info->p_slot;
-	struct controller *ctrl = p_slot->ctrl;
+	struct controller *ctrl = slot->ctrl;
+	u8 present;
 
-	mutex_lock(&p_slot->lock);
-	switch (info->event_type) {
-	case INT_BUTTON_PRESS:
-		handle_button_press_event(p_slot);
-		break;
-	case INT_POWER_FAULT:
-		if (!POWER_CTRL(ctrl))
-			break;
-		pciehp_set_attention_status(p_slot, 1);
-		pciehp_green_led_off(p_slot);
-		break;
-	case INT_PRESENCE_ON:
-		pciehp_queue_power_work(p_slot, ENABLE_REQ);
-		break;
-	case INT_PRESENCE_OFF:
-		/*
-		 * Regardless of surprise capability, we need to
-		 * definitely remove a card that has been pulled out!
-		 */
-		pciehp_queue_power_work(p_slot, DISABLE_REQ);
-		break;
-	case INT_LINK_UP:
-	case INT_LINK_DOWN:
-		handle_link_event(p_slot, info->event_type);
-		break;
-	default:
-		break;
+	mutex_lock(&slot->lock);
+	pciehp_get_adapter_status(slot, &present);
+	ctrl_info(ctrl, "Slot(%s): Card %spresent\n", slot_name(slot),
+		  present ? "" : "not ");
+
+	if (present) {
+		slot->state = POWERON_STATE;
+		mutex_unlock(&slot->lock);
+		pciehp_enable_slot(slot);
+	} else {
+		slot->state = POWEROFF_STATE;
+		mutex_unlock(&slot->lock);
+		pciehp_disable_slot(slot);
 	}
-	mutex_unlock(&p_slot->lock);
-
-	kfree(info);
 }
 
 /*