Re: Software suspend testing in 2.6.0-test1

Pavel Machek
2003-07-21T21:14:02Z

Hi!

> > But why do you touch PF_FROZEN here? Refrigerator should do that.
> > And wake_up_process should not be needed...
> > If it is in refrigerator, it polls PF_FREEZE...
>
> Note that the old code always called wake_up_process(), which is
> necessary to make the process run one more iteration in refrigerator()
> and relize that it is time to unfreeze.
>
> The patch changes things so that wake_up_process() is NOT called if
> the process is stopped at some other place than in refrigerator().
> This ensures that processes that were stopped before we invoked swsusp
> are still stopped after resume.

Yes, but you still print warning for them. I hopefully killed that.

> I manually clear PF_FREEZE here in an attempt to handle a race
> condition, but I realize I need to understand more of the scheduler
> and signal code before I know for sure if this is necessary and/or
> sufficient.

I do not see the race so I killed that... Here's what I applied.

Pavel

--- /usr/src/tmp/linux/kernel/suspend.c 2003-07-21 22:15:39.000000000 +0200
+++ /usr/src/linux/kernel/suspend.c 2003-07-21 22:11:28.000000000 +0200
@@ -5,7 +5,7 @@
* machine suspend feature using pretty near only high-level routines
*
* Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu>
- * Copyright (C) 1998,2001,2002 Pavel Machek <pavel@suse.cz>
+ * Copyright (C) 1998,2001-2003 Pavel Machek <pavel@suse.cz>
*
* I'd like to thank the following people for their work:
*
@@ -84,7 +84,6 @@
#define ADDRESS2(x) __ADDRESS(__pa(x)) /* Needed for x86-64 where some pages are in memory twice */

/* References to section boundaries */
-extern char _text, _etext, _edata, __bss_start, _end;
extern char __nosave_begin, __nosave_end;

extern int is_head_of_free_region(struct page *);
@@ -164,14 +163,21 @@
* Refrigerator and related stuff
*/

-#define INTERESTING(p) \
- /* We don't want to touch kernel_threads..*/ \
- if (p->flags & PF_IOTHREAD) \
- continue; \
- if (p == current) \
- continue; \
- if (p->state == TASK_ZOMBIE) \
- continue;
+/* 0 = Ignore this process when freezing/thawing, 1 = freeze/thaw this process */
+static inline int interesting_process(struct task_struct *p)
+{
+ if (p->flags & PF_IOTHREAD)
+ return 0;
+ if (p == current)
+ return 0;
+ if ((p->state == TASK_ZOMBIE) || (p->state == TASK_DEAD))
+ return 0;
+ if (p->state == TASK_STOPPED)
+ return 0;
+
+
+ return 1;
+}

#define TIMEOUT (6 * HZ) /* Timeout for stopping processes */

@@ -214,7 +220,8 @@
read_lock(&tasklist_lock);
do_each_thread(g, p) {
unsigned long flags;
- INTERESTING(p);
+ if (!interesting_process(p))
+ continue;
if (p->flags & PF_FROZEN)
continue;

@@ -247,13 +254,14 @@
printk( "Restarting tasks..." );
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- INTERESTING(p);
-
- if (p->flags & PF_FROZEN)
- p->flags &= ~PF_FROZEN;
- else
- printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
- wake_up_process(p);
+ if (!interesting_process(p))
+ continue;
+
+ if (p->flags & PF_FROZEN) {
+ p->flags &= ~PF_FROZEN;
+ wake_up_process(p);
+ } else
+ PRINTK(KERN_ERR " Strange, %s not frozen\n", p->comm );
} while_each_thread(g, p);

read_unlock(&tasklist_lock);

--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]