[PATCH] shpchp: event handling rework

The event handler of SHPCHP driver is unnecessarily very complex. In
addition, current event handler can only a fixed number of events at
the same time, and some of events would be lost if several number of
events happened at the same time.

This patch simplify the event handler by using 'work queue', and it
also fix the above-mentioned issue.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 89 insertions, 224 deletions

diff --git a/drivers/pci/hotplug/shpchp_ctrl.c b/drivers/pci/hotplug/shpchp_ctrl.c
index b709328a4145..2411f3bd08da 100644
--- a/drivers/pci/hotplug/shpchp_ctrl.c
+++ b/drivers/pci/hotplug/shpchp_ctrl.c
@@ -32,44 +32,46 @@
 #include <linux/types.h>
 #include <linux/smp_lock.h>
 #include <linux/pci.h>
+#include <linux/workqueue.h>
 #include "../pci.h"
 #include "shpchp.h"
 
-static void interrupt_event_handler(struct controller *ctrl);
+static void interrupt_event_handler(void *data);
 
-static struct semaphore event_semaphore;        /* mutex for process loop (up if something to process) */
-static struct semaphore event_exit;             /* guard ensure thread has exited before calling it quits */
-static int event_finished;
-static unsigned long pushbutton_pending;        /* = 0 */
+static int queue_interrupt_event(struct slot *p_slot, u32 event_type)
+{
+        struct event_info *info;
+
+        info = kmalloc(sizeof(*info), GFP_ATOMIC);
+        if (!info)
+                return -ENOMEM;
+
+        info->event_type = event_type;
+        info->p_slot = p_slot;
+        INIT_WORK(&info->work, interrupt_event_handler, info);
+
+        queue_work(shpchp_wq, &info->work);
+
+        return 0;
+}
 
 u8 shpchp_handle_attention_button(u8 hp_slot, void *inst_id)
 {
         struct controller *ctrl = (struct controller *) inst_id;
         struct slot *p_slot;
-        u8 rc = 0;
-        u8 getstatus;
-        struct event_info *taskInfo;
+        u32 event_type;
 
         /* Attention Button Change */
         dbg("shpchp:  Attention button interrupt received.\n");
         
-        /* This is the structure that tells the worker thread what to do */
-        taskInfo = &(ctrl->event_queue[ctrl->next_event]);
         p_slot = shpchp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
-
         p_slot->hpc_ops->get_adapter_status(p_slot, &(p_slot->presence_save));
-        p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
-        
-        ctrl->next_event = (ctrl->next_event + 1) % 10;
-        taskInfo->hp_slot = hp_slot;
-
-        rc++;
 
         /*
          *  Button pressed - See if need to TAKE ACTION!!!
          */
         info("Button pressed on Slot(%d)\n", ctrl->first_slot + hp_slot);
-        taskInfo->event_type = INT_BUTTON_PRESS;
+        event_type = INT_BUTTON_PRESS;
 
         if ((p_slot->state == BLINKINGON_STATE)
             || (p_slot->state == BLINKINGOFF_STATE)) {
@@ -77,7 +79,7 @@ u8 shpchp_handle_attention_button(u8 hp_slot, void *inst_id)
                  * attention again before the 5 sec. limit expires to cancel hot-add
                  * or hot-remove
                  */
-                taskInfo->event_type = INT_BUTTON_CANCEL;
+                event_type = INT_BUTTON_CANCEL;
                 info("Button cancel on Slot(%d)\n", ctrl->first_slot + hp_slot);
         } else if ((p_slot->state == POWERON_STATE)
                    || (p_slot->state == POWEROFF_STATE)) {
@@ -85,12 +87,11 @@ u8 shpchp_handle_attention_button(u8 hp_slot, void *inst_id)
                  * means that the previous attention button action to hot-add or
                  * hot-remove is undergoing
                  */
-                taskInfo->event_type = INT_BUTTON_IGNORE;
+                event_type = INT_BUTTON_IGNORE;
                 info("Button ignore on Slot(%d)\n", ctrl->first_slot + hp_slot);
         }
 
-        if (rc)
-                up(&event_semaphore);   /* signal event thread that new event is posted */
+        queue_interrupt_event(p_slot, event_type);
 
         return 0;
 
@@ -100,21 +101,12 @@ u8 shpchp_handle_switch_change(u8 hp_slot, void *inst_id)
 {
         struct controller *ctrl = (struct controller *) inst_id;
         struct slot *p_slot;
-        u8 rc = 0;
         u8 getstatus;
-        struct event_info *taskInfo;
+        u32 event_type;
 
         /* Switch Change */
         dbg("shpchp:  Switch interrupt received.\n");
 
-        /* This is the structure that tells the worker thread
-         * what to do
-         */
-        taskInfo = &(ctrl->event_queue[ctrl->next_event]);
-        ctrl->next_event = (ctrl->next_event + 1) % 10;
-        taskInfo->hp_slot = hp_slot;
-
-        rc++;
         p_slot = shpchp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
         p_slot->hpc_ops->get_adapter_status(p_slot, &(p_slot->presence_save));
         p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
@@ -126,9 +118,9 @@ u8 shpchp_handle_switch_change(u8 hp_slot, void *inst_id)
                  * Switch opened
                  */
                 info("Latch open on Slot(%d)\n", ctrl->first_slot + hp_slot);
-                taskInfo->event_type = INT_SWITCH_OPEN;
+                event_type = INT_SWITCH_OPEN;
                 if (p_slot->pwr_save && p_slot->presence_save) {
-                        taskInfo->event_type = INT_POWER_FAULT;
+                        event_type = INT_POWER_FAULT;
                         err("Surprise Removal of card\n");
                 }
         } else {
@@ -136,34 +128,23 @@ u8 shpchp_handle_switch_change(u8 hp_slot, void *inst_id)
                  *  Switch closed
                  */
                 info("Latch close on Slot(%d)\n", ctrl->first_slot + hp_slot);
-                taskInfo->event_type = INT_SWITCH_CLOSE;
+                event_type = INT_SWITCH_CLOSE;
         }
 
-        if (rc)
-                up(&event_semaphore);   /* signal event thread that new event is posted */
+        queue_interrupt_event(p_slot, event_type);
 
-        return rc;
+        return 1;
 }
 
 u8 shpchp_handle_presence_change(u8 hp_slot, void *inst_id)
 {
         struct controller *ctrl = (struct controller *) inst_id;
         struct slot *p_slot;
-        u8 rc = 0;
-        /*u8 temp_byte;*/
-        struct event_info *taskInfo;
+        u32 event_type;
 
         /* Presence Change */
         dbg("shpchp:  Presence/Notify input change.\n");
 
-        /* This is the structure that tells the worker thread
-         * what to do
-         */
-        taskInfo = &(ctrl->event_queue[ctrl->next_event]);
-        ctrl->next_event = (ctrl->next_event + 1) % 10;
-        taskInfo->hp_slot = hp_slot;
-
-        rc++;
         p_slot = shpchp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
 
         /* 
@@ -175,39 +156,29 @@ u8 shpchp_handle_presence_change(u8 hp_slot, void *inst_id)
                  * Card Present
                  */
                 info("Card present on Slot(%d)\n", ctrl->first_slot + hp_slot);
-                taskInfo->event_type = INT_PRESENCE_ON;
+                event_type = INT_PRESENCE_ON;
         } else {
                 /*
                  * Not Present
                  */
                 info("Card not present on Slot(%d)\n", ctrl->first_slot + hp_slot);
-                taskInfo->event_type = INT_PRESENCE_OFF;
+                event_type = INT_PRESENCE_OFF;
         }
 
-        if (rc)
-                up(&event_semaphore);   /* signal event thread that new event is posted */
+        queue_interrupt_event(p_slot, event_type);
 
-        return rc;
+        return 1;
 }
 
 u8 shpchp_handle_power_fault(u8 hp_slot, void *inst_id)
 {
         struct controller *ctrl = (struct controller *) inst_id;
         struct slot *p_slot;
-        u8 rc = 0;
-        struct event_info *taskInfo;
+        u32 event_type;
 
         /* Power fault */
         dbg("shpchp:  Power fault interrupt received.\n");
 
-        /* This is the structure that tells the worker thread
-         * what to do
-         */
-        taskInfo = &(ctrl->event_queue[ctrl->next_event]);
-        ctrl->next_event = (ctrl->next_event + 1) % 10;
-        taskInfo->hp_slot = hp_slot;
-
-        rc++;
         p_slot = shpchp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
 
         if ( !(p_slot->hpc_ops->query_power_fault(p_slot))) {
@@ -216,21 +187,21 @@ u8 shpchp_handle_power_fault(u8 hp_slot, void *inst_id)
                  */
                 info("Power fault cleared on Slot(%d)\n", ctrl->first_slot + hp_slot);
                 p_slot->status = 0x00;
-                taskInfo->event_type = INT_POWER_FAULT_CLEAR;
+                event_type = INT_POWER_FAULT_CLEAR;
         } else {
                 /*
                  *   Power fault
                  */
                 info("Power fault on Slot(%d)\n", ctrl->first_slot + hp_slot);
-                taskInfo->event_type = INT_POWER_FAULT;
+                event_type = INT_POWER_FAULT;
                 /* set power fault status for this board */
                 p_slot->status = 0xFF;
                 info("power fault bit %x set\n", hp_slot);
         }
-        if (rc)
-                up(&event_semaphore);   /* signal event thread that new event is posted */
 
-        return rc;
+        queue_interrupt_event(p_slot, event_type);
+
+        return 1;
 }
 
 /* The following routines constitute the bulk of the 
@@ -521,14 +492,6 @@ static int remove_board(struct slot *p_slot)
 }
 
 
-static void pushbutton_helper_thread (unsigned long data)
-{
-        pushbutton_pending = data;
-
-        up(&event_semaphore);
-}
-
-
 /**
  * shpchp_pushbutton_thread
  *
@@ -536,90 +499,24 @@ static void pushbutton_helper_thread (unsigned long data)
  * Handles all pending events and exits.
  *
  */
-static void shpchp_pushbutton_thread (unsigned long slot)
+void shpchp_pushbutton_thread(void *data)
 {
-        struct slot *p_slot = (struct slot *) slot;
+        struct slot *p_slot = data;
         u8 getstatus;
-        
-        pushbutton_pending = 0;
-
-        if (!p_slot) {
-                dbg("%s: Error! slot NULL\n", __FUNCTION__);
-                return;
-        }
 
         p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
         if (getstatus) {
                 p_slot->state = POWEROFF_STATE;
-
                 shpchp_disable_slot(p_slot);
                 p_slot->state = STATIC_STATE;
         } else {
                 p_slot->state = POWERON_STATE;
-
                 if (shpchp_enable_slot(p_slot))
                         p_slot->hpc_ops->green_led_off(p_slot);
-
                 p_slot->state = STATIC_STATE;
         }
-
-        return;
-}
-
-
-/* this is the main worker thread */
-static int event_thread(void* data)
-{
-        struct controller *ctrl;
-        lock_kernel();
-        daemonize("shpchpd_event");
-        unlock_kernel();
-
-        while (1) {
-                dbg("!!!!event_thread sleeping\n");
-                down_interruptible (&event_semaphore);
-                dbg("event_thread woken finished = %d\n", event_finished);
-                if (event_finished || signal_pending(current))
-                        break;
-                /* Do stuff here */
-                if (pushbutton_pending)
-                        shpchp_pushbutton_thread(pushbutton_pending);
-                else
-                        list_for_each_entry(ctrl, &shpchp_ctrl_list, ctrl_list)
-                                interrupt_event_handler(ctrl);
-        }
-        dbg("event_thread signals exit\n");
-        up(&event_exit);
-        return 0;
-}
-
-int shpchp_event_start_thread (void)
-{
-        int pid;
-
-        /* initialize our semaphores */
-        init_MUTEX_LOCKED(&event_exit);
-        event_finished=0;
-
-        init_MUTEX_LOCKED(&event_semaphore);
-        pid = kernel_thread(event_thread, NULL, 0);
-
-        if (pid < 0) {
-                err ("Can't start up our event thread\n");
-                return -1;
-        }
-        return 0;
-}
-
-
-void shpchp_event_stop_thread (void)
-{
-        event_finished = 1;
-        up(&event_semaphore);
-        down(&event_exit);
 }
 
-
 static int update_slot_info (struct slot *slot)
 {
         struct hotplug_slot_info *info;
@@ -639,91 +536,59 @@ static int update_slot_info (struct slot *slot)
         return result;
 }
 
-static void interrupt_event_handler(struct controller *ctrl)
+static void interrupt_event_handler(void *data)
 {
-        int loop = 0;
-        int change = 1;
-        u8 hp_slot;
+        struct event_info *info = data;
+        struct slot *p_slot = info->p_slot;
         u8 getstatus;
-        struct slot *p_slot;
 
-        while (change) {
-                change = 0;
-
-                for (loop = 0; loop < 10; loop++) {
-                        if (ctrl->event_queue[loop].event_type != 0) {
-                                dbg("%s:loop %x event_type %x\n", __FUNCTION__, loop, 
-                                        ctrl->event_queue[loop].event_type);
-                                hp_slot = ctrl->event_queue[loop].hp_slot;
-
-                                p_slot = shpchp_find_slot(ctrl, hp_slot + ctrl->slot_device_offset);
-
-                                if (ctrl->event_queue[loop].event_type == INT_BUTTON_CANCEL) {
-                                        dbg("%s: button cancel\n", __FUNCTION__);
-                                        del_timer(&p_slot->task_event);
-
-                                        switch (p_slot->state) {
-                                        case BLINKINGOFF_STATE:
-                                                p_slot->hpc_ops->green_led_on(p_slot);
-                                                p_slot->hpc_ops->set_attention_status(p_slot, 0);
-                                                break;
-                                        case BLINKINGON_STATE:
-                                                p_slot->hpc_ops->green_led_off(p_slot);
-                                                p_slot->hpc_ops->set_attention_status(p_slot, 0);
-                                                break;
-                                        default:
-                                                warn("Not a valid state\n");
-                                                return;
-                                        }
-                                        info(msg_button_cancel, p_slot->number);
-                                        p_slot->state = STATIC_STATE;
-                                } else if (ctrl->event_queue[loop].event_type == INT_BUTTON_PRESS) {
-                                        /* Button Pressed (No action on 1st press...) */
-                                        dbg("%s: Button pressed\n", __FUNCTION__);
-
-                                        p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
-                                        if (getstatus) {
-                                                /* slot is on */
-                                                dbg("%s: slot is on\n", __FUNCTION__);
-                                                p_slot->state = BLINKINGOFF_STATE;
-                                                info(msg_button_off, p_slot->number);
-                                        } else {
-                                                /* slot is off */
-                                                dbg("%s: slot is off\n", __FUNCTION__);
-                                                p_slot->state = BLINKINGON_STATE;
-                                                info(msg_button_on, p_slot->number);
-                                        }
-
-                                        /* blink green LED and turn off amber */
-                                        p_slot->hpc_ops->green_led_blink(p_slot);
-                                        p_slot->hpc_ops->set_attention_status(p_slot, 0);
-
-                                        init_timer(&p_slot->task_event);
-                                        p_slot->task_event.expires = jiffies + 5 * HZ;   /* 5 second delay */
-                                        p_slot->task_event.function = (void (*)(unsigned long)) pushbutton_helper_thread;
-                                        p_slot->task_event.data = (unsigned long) p_slot;
-
-                                        dbg("%s: add_timer p_slot = %p\n", __FUNCTION__,(void *) p_slot);
-                                        add_timer(&p_slot->task_event);
-                                } else if (ctrl->event_queue[loop].event_type == INT_POWER_FAULT) {
-                                        /***********POWER FAULT********************/
-                                        dbg("%s: power fault\n", __FUNCTION__);
-                                        p_slot->hpc_ops->set_attention_status(p_slot, 1);
-                                        p_slot->hpc_ops->green_led_off(p_slot);
-                                } else {
-                                        /* refresh notification */
-                                        if (p_slot)
-                                                update_slot_info(p_slot);
-                                }
-
-                                ctrl->event_queue[loop].event_type = 0;
+        switch (info->event_type) {
+        case INT_BUTTON_CANCEL:
+                dbg("%s: button cancel\n", __FUNCTION__);
+                cancel_delayed_work(&p_slot->work);
+                switch (p_slot->state) {
+                case BLINKINGOFF_STATE:
+                        p_slot->hpc_ops->green_led_on(p_slot);
+                        p_slot->hpc_ops->set_attention_status(p_slot, 0);
+                        break;
+                case BLINKINGON_STATE:
+                        p_slot->hpc_ops->green_led_off(p_slot);
+                        p_slot->hpc_ops->set_attention_status(p_slot, 0);
+                        break;
+                default:
+                        warn("Not a valid state\n");
+                        return;
+                }
+                info(msg_button_cancel, p_slot->number);
+                p_slot->state = STATIC_STATE;
+                break;
+        case INT_BUTTON_PRESS:
+                dbg("%s: Button pressed\n", __FUNCTION__);
+                p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
+                if (getstatus) {
+                        p_slot->state = BLINKINGOFF_STATE;
+                        info(msg_button_off, p_slot->number);
+                } else {
+                        p_slot->state = BLINKINGON_STATE;
+                        info(msg_button_on, p_slot->number);
+                }
+                /* blink green LED and turn off amber */
+                p_slot->hpc_ops->green_led_blink(p_slot);
+                p_slot->hpc_ops->set_attention_status(p_slot, 0);
 
-                                change = 1;
-                        }
-                }               /* End of FOR loop */
+                queue_delayed_work(shpchp_wq, &p_slot->work, 5*HZ);
+                break;
+        case INT_POWER_FAULT:
+                dbg("%s: power fault\n", __FUNCTION__);
+                p_slot->hpc_ops->set_attention_status(p_slot, 1);
+                p_slot->hpc_ops->green_led_off(p_slot);
+                break;
+        default:
+                update_slot_info(p_slot);
+                break;
         }
 
-        return;
+        kfree(info);
 }