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Message-ID: <20070422121524.GD20763@infradead.org>
Date: Sun, 22 Apr 2007 13:15:24 +0100
From: Christoph Hellwig <hch@...radead.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Linux Containers <containers@...ts.osdl.org>,
Oleg Nesterov <oleg@...sign.ru>,
Christoph Hellwig <hch@...radead.org>,
linux-kernel@...r.kernel.org, greg@...ah.com,
kristen.c.accardi@...el.com
Subject: Re: Remaining straight forward kthread API conversions...
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@....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);
}
}
-
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