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Message-ID: <20070422121208.GC20763@infradead.org>
Date: Sun, 22 Apr 2007 13:12:08 +0100
From: Christoph Hellwig <hch@...radead.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: "<Andrew Morton" <akpm@...l.org>, containers@...ts.osdl.org,
Oleg Nesterov <oleg@...sign.ru>, linux-kernel@...r.kernel.org,
gregkh@...e.de
Subject: Re: [PATCH] cpqphp: Convert to use the kthread API
On Thu, Apr 19, 2007 at 12:55:31AM -0600, Eric W. Biederman wrote:
> From: Eric W. Biederman <ebiederm@...ssion.com> - unquoted
>
> This patch changes cpqphp to use kthread_run and not
> kernel_thread and daemonize to startup and setup
> the cpqphp thread.
Thread handling in this driver (and actually everything else) seems
to be written by a crackmonkey.
Here's my take at fixing everything slightly related to thread handling
up:
- full switch to kthread infrastructure
- remove unused semaphore as mutex and waitqueue in long_delay -
in fact that whole function should just go away as the user would
be a lot more happy with just msleep_interruptible.
- use wake_up_process for waking the thread
Signed-off-by: Christoph Hellwig <hch@....de>
Index: linux-2.6/drivers/pci/hotplug/cpqphp_ctrl.c
===================================================================
--- linux-2.6.orig/drivers/pci/hotplug/cpqphp_ctrl.c 2007-04-22 12:46:33.000000000 +0200
+++ linux-2.6/drivers/pci/hotplug/cpqphp_ctrl.c 2007-04-22 12:53:58.000000000 +0200
@@ -37,6 +37,7 @@
#include <linux/smp_lock.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
+#include <linux/kthread.h>
#include "cpqphp.h"
static u32 configure_new_device(struct controller* ctrl, struct pci_func *func,
@@ -45,34 +46,20 @@ static int configure_new_function(struct
u8 behind_bridge, struct resource_lists *resources);
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 unsigned long pushbutton_pending; /* = 0 */
-/* things needed for the long_delay function */
-static struct semaphore delay_sem;
-static wait_queue_head_t delay_wait;
+static struct task_struct *cpqhp_event_thread;
+static unsigned long pushbutton_pending; /* = 0 */
/* delay is in jiffies to wait for */
static void long_delay(int delay)
{
- DECLARE_WAITQUEUE(wait, current);
-
- /* only allow 1 customer into the delay queue at once
- * yes this makes some people wait even longer, but who really cares?
- * this is for _huge_ delays to make the hardware happy as the
- * signals bounce around
+ /*
+ * XXX(hch): if someone is bored please convert all callers
+ * to call msleep_interruptible directly. They really want
+ * to specify timeouts in natural units and spend a lot of
+ * effort converting them to jiffies..
*/
- down (&delay_sem);
-
- init_waitqueue_head(&delay_wait);
-
- add_wait_queue(&delay_wait, &wait);
msleep_interruptible(jiffies_to_msecs(delay));
- remove_wait_queue(&delay_wait, &wait);
-
- up(&delay_sem);
}
@@ -955,8 +942,8 @@ irqreturn_t cpqhp_ctrl_intr(int IRQ, voi
}
if (schedule_flag) {
- up(&event_semaphore);
- dbg("Signal event_semaphore\n");
+ wake_up_process(cpqhp_event_thread);
+ dbg("Waking even thread");
}
return IRQ_HANDLED;
}
@@ -1738,7 +1725,7 @@ static u32 remove_board(struct pci_func
static void pushbutton_helper_thread(unsigned long data)
{
pushbutton_pending = data;
- up(&event_semaphore);
+ wake_up_process(cpqhp_event_thread);
}
@@ -1746,16 +1733,14 @@ static void pushbutton_helper_thread(uns
static int event_thread(void* data)
{
struct controller *ctrl;
- lock_kernel();
- daemonize("phpd_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) break;
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
+
+ if (kthread_should_stop())
+ break;
/* Do stuff here */
if (pushbutton_pending)
cpqhp_pushbutton_thread(pushbutton_pending);
@@ -1764,38 +1749,24 @@ static int event_thread(void* data)
interrupt_event_handler(ctrl);
}
dbg("event_thread signals exit\n");
- up(&event_exit);
return 0;
}
-
int cpqhp_event_start_thread(void)
{
- int pid;
-
- /* initialize our semaphores */
- init_MUTEX(&delay_sem);
- init_MUTEX_LOCKED(&event_semaphore);
- init_MUTEX_LOCKED(&event_exit);
- event_finished=0;
-
- pid = kernel_thread(event_thread, NULL, 0);
- if (pid < 0) {
+ cpqhp_event_thread = kthread_run(event_thread, NULL, "phpd_event");
+ if (IS_ERR(cpqhp_event_thread)) {
err ("Can't start up our event thread\n");
- return -1;
+ return PTR_ERR(cpqhp_event_thread);
}
- dbg("Our event thread pid = %d\n", pid);
+
return 0;
}
void cpqhp_event_stop_thread(void)
{
- event_finished = 1;
- dbg("event_thread finish command given\n");
- up(&event_semaphore);
- dbg("wait for event_thread to exit\n");
- down(&event_exit);
+ kthread_stop(cpqhp_event_thread);
}
-
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