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Message-ID: <Pine.LNX.4.64.0705071412030.3671@rancor.yyz.somanetworks.com>
Date: Mon, 7 May 2007 14:18:29 -0400 (EDT)
From: Scott Murray <scottm@...anetworks.com>
To: "<Andrew Morton" <akpm@...l.org>
cc: Christoph Hellwig <hch@...radead.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
containers@...ts.osdl.org, Oleg Nesterov <oleg@...sign.ru>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
kristen.c.accardi@...el.com
Subject: Re: [PATCH] cpci_hotplug: Convert to use the kthread API
On Fri, 4 May 2007, Christoph Hellwig wrote:
> On Fri, Apr 27, 2007 at 06:07:49PM -0400, Scott Murray wrote:
> > Sorry, it took me a few days to get to testing this out. It looks good,
> > but I had to make a couple of tweaks to avoid a hang when rmmod'ing a
> > board driver. The board drivers do:
> >
> > cpci_hp_stop()
> > cpci_hp_unregister_controller(controller)
> >
> > to shutdown, and the check in cpci_hp_unregister_controller if the thread
> > is running wasn't working due to a bit too much code being excised. The
> > result was kthread_stop being called twice, which hangs. I've indicated
> > my changes to avoid this inline below.
>
> Can you forward the patches with your fix to Andrew to make sure he
> picks it up?
Andrew, here is my updated version of Christoph's kthread conversion
patch for cpci_hotplug. I've CC'ed Kristen so she won't be surprised
when this eventually goes to mainline.
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Scott Murray <scottm@...anetworks.com>
---
diff --git a/drivers/pci/hotplug/cpci_hotplug_core.c b/drivers/pci/hotplug/cpci_hotplug_core.c
index 6845515..ed4d44e 100644
--- a/drivers/pci/hotplug/cpci_hotplug_core.c
+++ b/drivers/pci/hotplug/cpci_hotplug_core.c
@@ -35,6 +35,7 @@
#include <linux/smp_lock.h>
#include <asm/atomic.h>
#include <linux/delay.h>
+#include <linux/kthread.h>
#include "cpci_hotplug.h"
#define DRIVER_AUTHOR "Scott Murray <scottm@...anetworks.com>"
@@ -59,9 +60,8 @@ static int slots;
static atomic_t extracting;
int cpci_debug;
static struct cpci_hp_controller *controller;
-static struct semaphore event_semaphore; /* mutex for process loop (up if something to process) */
-static struct semaphore thread_exit; /* guard ensure thread has exited before calling it quits */
-static int thread_finished = 1;
+static struct task_struct *cpci_thread;
+static int thread_finished;
static int enable_slot(struct hotplug_slot *slot);
static int disable_slot(struct hotplug_slot *slot);
@@ -357,9 +357,7 @@ cpci_hp_intr(int irq, void *data)
controller->ops->disable_irq();
/* Trigger processing by the event thread */
- dbg("Signal event_semaphore");
- up(&event_semaphore);
- dbg("exited cpci_hp_intr");
+ wake_up_process(cpci_thread);
return IRQ_HANDLED;
}
@@ -521,17 +519,12 @@ event_thread(void *data)
{
int rc;
- lock_kernel();
- daemonize("cpci_hp_eventd");
- unlock_kernel();
-
dbg("%s - event thread started", __FUNCTION__);
while (1) {
dbg("event thread sleeping");
- down_interruptible(&event_semaphore);
- dbg("event thread woken, thread_finished = %d",
- thread_finished);
- if (thread_finished || signal_pending(current))
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
+ if (kthread_should_stop())
break;
do {
rc = check_slots();
@@ -541,18 +534,17 @@ event_thread(void *data)
} else if (rc < 0) {
dbg("%s - error checking slots", __FUNCTION__);
thread_finished = 1;
- break;
+ goto out;
}
- } while (atomic_read(&extracting) && !thread_finished);
- if (thread_finished)
+ } while (atomic_read(&extracting) && !kthread_should_stop());
+ if (kthread_should_stop())
break;
/* Re-enable ENUM# interrupt */
dbg("%s - re-enabling irq", __FUNCTION__);
controller->ops->enable_irq();
}
- dbg("%s - event thread signals exit", __FUNCTION__);
- up(&thread_exit);
+ out:
return 0;
}
@@ -562,12 +554,8 @@ poll_thread(void *data)
{
int rc;
- lock_kernel();
- daemonize("cpci_hp_polld");
- unlock_kernel();
-
while (1) {
- if (thread_finished || signal_pending(current))
+ if (kthread_should_stop() || signal_pending(current))
break;
if (controller->ops->query_enum()) {
do {
@@ -578,48 +566,36 @@ poll_thread(void *data)
} else if (rc < 0) {
dbg("%s - error checking slots", __FUNCTION__);
thread_finished = 1;
- break;
+ goto out;
}
- } while (atomic_read(&extracting) && !thread_finished);
+ } while (atomic_read(&extracting) && !kthread_should_stop());
}
msleep(100);
}
- dbg("poll thread signals exit");
- up(&thread_exit);
+ out:
return 0;
}
static int
cpci_start_thread(void)
{
- int pid;
-
- /* initialize our semaphores */
- init_MUTEX_LOCKED(&event_semaphore);
- init_MUTEX_LOCKED(&thread_exit);
- thread_finished = 0;
-
if (controller->irq)
- pid = kernel_thread(event_thread, NULL, 0);
+ cpci_thread = kthread_run(event_thread, NULL, "cpci_hp_eventd");
else
- pid = kernel_thread(poll_thread, NULL, 0);
- if (pid < 0) {
+ cpci_thread = kthread_run(poll_thread, NULL, "cpci_hp_polld");
+ if (IS_ERR(cpci_thread)) {
err("Can't start up our thread");
- return -1;
+ return PTR_ERR(cpci_thread);
}
- dbg("Our thread pid = %d", pid);
+ thread_finished = 0;
return 0;
}
static void
cpci_stop_thread(void)
{
+ kthread_stop(cpci_thread);
thread_finished = 1;
- dbg("thread finish command given");
- if (controller->irq)
- up(&event_semaphore);
- dbg("wait for thread to exit");
- down(&thread_exit);
}
int
--
Scott Murray
SOMA Networks, Inc.
Toronto, Ontario
e-mail: scottm@...anetworks.com
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