Re: Remaining straight forward kthread API conversions...

[Christoph Hellwig <hch@infradead.org>]

Looks like you were missing at least the pcie hotplug driver.  Another
one of the horrible thread abuses in drivers/pci/hotpug.

 - full conversion to kthread infrastructure
 - use wake_up_process to wake the thread up

Like most pci hotplug drivers it still uses very race non-atomic variable
assignment to communicated with the thread, but that's something the
maintainers should look into.


Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/drivers/pci/hotplug/pciehp_ctrl.c
===================================================================
--- linux-2.6.orig/drivers/pci/hotplug/pciehp_ctrl.c	2007-04-22 11:36:58.000000000 +0200
+++ linux-2.6/drivers/pci/hotplug/pciehp_ctrl.c	2007-04-22 11:42:56.000000000 +0200
@@ -32,14 +32,13 @@
 #include <linux/types.h>
 #include <linux/smp_lock.h>
 #include <linux/pci.h>
+#include <linux/kthread.h>
 #include "../pci.h"
 #include "pciehp.h"
 
 static void interrupt_event_handler(struct controller *ctrl);
 
-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 struct task_struct *pciehpd_event_thread;
 static unsigned long pushbutton_pending;	/* = 0 */
 static unsigned long surprise_rm_pending;	/* = 0 */
 
@@ -93,8 +92,9 @@ u8 pciehp_handle_attention_button(u8 hp_
 		info("Button ignore on Slot(%s)\n", slot_name(p_slot));
 	}
 
+	/* signal event thread that new event is posted */
 	if (rc)
-		up(&event_semaphore);	/* signal event thread that new event is posted */
+		wake_up_process(pciehpd_event_thread);
 
 	return 0;
 
@@ -135,8 +135,9 @@ u8 pciehp_handle_switch_change(u8 hp_slo
 		taskInfo->event_type = INT_SWITCH_CLOSE;
 	}
 
+	/* signal event thread that new event is posted */
 	if (rc)
-		up(&event_semaphore);	/* signal event thread that new event is posted */
+		wake_up_process(pciehpd_event_thread);
 
 	return rc;
 }
@@ -178,8 +179,9 @@ u8 pciehp_handle_presence_change(u8 hp_s
 		taskInfo->event_type = INT_PRESENCE_OFF;
 	}
 
+	/* signal event thread that new event is posted */
 	if (rc)
-		up(&event_semaphore);	/* signal event thread that new event is posted */
+		wake_up_process(pciehpd_event_thread);
 
 	return rc;
 }
@@ -217,8 +219,10 @@ u8 pciehp_handle_power_fault(u8 hp_slot,
 		taskInfo->event_type = INT_POWER_FAULT;
 		info("power fault bit %x set\n", hp_slot);
 	}
+
+	/* signal event thread that new event is posted */
 	if (rc)
-		up(&event_semaphore);	/* signal event thread that new event is posted */
+		wake_up_process(pciehpd_event_thread);
 
 	return rc;
 }
@@ -362,7 +366,7 @@ static void pushbutton_helper_thread(uns
 {
 	pushbutton_pending = data;
 
-	up(&event_semaphore);
+	wake_up_process(pciehpd_event_thread);
 }
 
 /**
@@ -452,19 +456,14 @@ static void pciehp_surprise_rm_thread(un
 
 
 /* this is the main worker thread */
-static int event_thread(void* data)
+static int event_thread(void *data)
 {
 	struct controller *ctrl;
-	lock_kernel();
-	daemonize("pciehpd_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))
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+		if (kthread_should_stop())
 			break;
 		/* Do stuff here */
 		if (pushbutton_pending)
@@ -476,24 +475,15 @@ static int event_thread(void* data)
 				interrupt_event_handler(ctrl);
 	}
 	dbg("event_thread signals exit\n");
-	up(&event_exit);
 	return 0;
 }
 
 int pciehp_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) {
+	pciehpd_event_thread = kthread_run(event_thread, NULL, "pciehpd_event");
+	if (IS_ERR(pciehpd_event_thread)) {
 		err ("Can't start up our event thread\n");
-		return -1;
+		return PTR_ERR(pciehpd_event_thread);
 	}
 	return 0;
 }
@@ -501,9 +491,7 @@ int pciehp_event_start_thread(void)
 
 void pciehp_event_stop_thread(void)
 {
-	event_finished = 1;
-	up(&event_semaphore);
-	down(&event_exit);
+	kthread_stop(pciehpd_event_thread);
 }
 
 
@@ -624,7 +612,7 @@ static void interrupt_event_handler(stru
 						dbg("Surprise Removal\n");
 						if (p_slot) {
 							surprise_rm_pending = (unsigned long) p_slot;
-							up(&event_semaphore);
+							wake_up_process(pciehpd_event_thread);
 							update_slot_info(p_slot);
 						}
 					}