Re: [linux-pm] [RFC] ACPI vs device ordering on resume

["Rafael J. Wysocki" <rjw@sisk.pl>]

Hi,

On Friday, 1 December 2006 10:33, Pavel Machek wrote:
> Hi!
> 
> > > So it looks like we need this sequence:
> > > 
> > > enable_nonboot_cpus() /* INIT */
> > > finish()	/* _WAK */
> > > device_resume()
> > 
> > Can somebody remind me about this immediately after 2.6.19?
> 
> Remind. But note that freezer is not yet SMP safe... Rafael is working
> on that.

Yup.

BTW, have you looked at the last version of the patch for the handling of
stopped tasks (appended just in case, full discussion at:
http://lists.osdl.org/pipermail/linux-pm/2006-November/004214.html)?

Rafael


Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/process.c |   36 ++++++++++++++++++++++++++++++------
 kernel/signal.c        |    2 +-
 2 files changed, 31 insertions(+), 7 deletions(-)

Index: linux-2.6.19-rc6-mm2/kernel/power/process.c
===================================================================
--- linux-2.6.19-rc6-mm2.orig/kernel/power/process.c
+++ linux-2.6.19-rc6-mm2/kernel/power/process.c
@@ -28,8 +28,7 @@ static inline int freezeable(struct task
 	if ((p == current) || 
 	    (p->flags & PF_NOFREEZE) ||
 	    (p->exit_state == EXIT_ZOMBIE) ||
-	    (p->exit_state == EXIT_DEAD) ||
-	    (p->state == TASK_STOPPED))
+	    (p->exit_state == EXIT_DEAD))
 		return 0;
 	return 1;
 }
@@ -81,6 +80,11 @@ static void cancel_freezing(struct task_
 	}
 }
 
+static inline int stopped_and_freezing(struct task_struct *p)
+{
+	return p->state == TASK_STOPPED && freezing(p);
+}
+
 static inline int is_user_space(struct task_struct *p)
 {
 	return p->mm && !(p->flags & PF_BORROWED_MM);
@@ -103,9 +107,11 @@ static unsigned int try_to_freeze_tasks(
 			if (frozen(p))
 				continue;
 
-			if (p->state == TASK_TRACED &&
-			    (frozen(p->parent) ||
-			     p->parent->state == TASK_STOPPED)) {
+			if (stopped_and_freezing(p))
+				continue;
+
+			if (p->state == TASK_TRACED && (frozen(p->parent) ||
+			    stopped_and_freezing(p->parent))) {
 				cancel_freezing(p);
 				continue;
 			}
@@ -149,7 +155,8 @@ static unsigned int try_to_freeze_tasks(
 			if (is_user_space(p) == !freeze_user_space)
 				continue;
 
-			if (freezeable(p) && !frozen(p))
+			if (freezeable(p) && !frozen(p) &&
+			    p->state != TASK_STOPPED && p->state != TASK_TRACED)
 				printk(KERN_ERR " %s\n", p->comm);
 
 			cancel_freezing(p);
@@ -185,6 +192,18 @@ int freeze_processes(void)
 	return 0;
 }
 
+static void release_stopped_tasks(void)
+{
+	struct task_struct *g, *p;
+
+	read_lock(&tasklist_lock);
+	do_each_thread(g, p) {
+		if (stopped_and_freezing(p))
+			cancel_freezing(p);
+	} while_each_thread(g, p);
+	read_unlock(&tasklist_lock);
+}
+
 static void thaw_tasks(int thaw_user_space)
 {
 	struct task_struct *g, *p;
@@ -197,6 +216,10 @@ static void thaw_tasks(int thaw_user_spa
 		if (is_user_space(p) == !thaw_user_space)
 			continue;
 
+		if (!frozen(p) &&
+		    (p->state == TASK_STOPPED || p->state == TASK_TRACED))
+			continue;
+
 		if (!thaw_process(p))
 			printk(KERN_WARNING " Strange, %s not stopped\n",
 				p->comm );
@@ -207,6 +230,7 @@ static void thaw_tasks(int thaw_user_spa
 void thaw_processes(void)
 {
 	printk("Restarting tasks ... ");
+	release_stopped_tasks();
 	thaw_tasks(FREEZER_KERNEL_THREADS);
 	thaw_tasks(FREEZER_USER_SPACE);
 	schedule();
Index: linux-2.6.19-rc6-mm2/kernel/signal.c
===================================================================
--- linux-2.6.19-rc6-mm2.orig/kernel/signal.c
+++ linux-2.6.19-rc6-mm2/kernel/signal.c
@@ -1937,9 +1937,9 @@ int get_signal_to_deliver(siginfo_t *inf
 	sigset_t *mask = &current->blocked;
 	int signr = 0;
 
+relock:
 	try_to_freeze();
 
-relock:
 	spin_lock_irq(&current->sighand->siglock);
 	for (;;) {
 		struct k_sigaction *ka;