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Message-Id: <200611191305.02250.rjw@sisk.pl>
Date: Sun, 19 Nov 2006 13:05:01 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Pavel Machek <pavel@....cz>
Cc: Andrew Morton <akpm@...l.org>, LKML <linux-kernel@...r.kernel.org>,
Nigel Cunningham <ncunningham@...uxmail.org>
Subject: Re: [PATCH 2/4] swsusp: Untangle freeze_processes
Hi,
On Sunday, 19 November 2006 03:09, Pavel Machek wrote:
> Hi!
>
> > Move the loop from freeze_processes() to a separate function and call it
> > independently for user space processes and kernel threads so that the order of
> > freezing tasks is clearly visible.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > ---
> > kernel/power/process.c | 88 ++++++++++++++++++++++++++++++++-----------------
> > 1 file changed, 58 insertions(+), 30 deletions(-)
> >
>
> > do_each_thread(g, p) {
> > + if (is_user_space(p)) {
> > + if(!freeze_user_space)
> > + continue;
> > + } else {
> > + if(freeze_user_space)
> > + continue;
> > + }
>
> Needs space between if and (, but lets use if (is_user_space() !=
> freeze_user_space) trick here, too.
OK
New version of the patch follows.
---
Move the loop from freeze_processes() to a separate function and call it
independently for user space processes and kernel threads so that the order of
freezing tasks is clearly visible.
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
kernel/power/process.c | 84 +++++++++++++++++++++++++++++++------------------
1 file changed, 54 insertions(+), 30 deletions(-)
Index: linux-2.6.19-rc5-mm2/kernel/power/process.c
===================================================================
--- linux-2.6.19-rc5-mm2.orig/kernel/power/process.c
+++ linux-2.6.19-rc5-mm2/kernel/power/process.c
@@ -86,24 +86,23 @@ static inline int is_user_space(struct t
return p->mm && !(p->flags & PF_BORROWED_MM);
}
-/* 0 = success, else # of processes that we failed to stop */
-int freeze_processes(void)
+static unsigned int try_to_freeze_tasks(int freeze_user_space)
{
- int todo, nr_user, user_frozen;
- unsigned long start_time;
struct task_struct *g, *p;
+ unsigned long end_time;
+ unsigned int todo;
- printk("Stopping tasks... ");
- start_time = jiffies;
- user_frozen = 0;
+ end_time = jiffies + TIMEOUT;
do {
- nr_user = todo = 0;
+ todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
+
if (frozen(p))
continue;
+
if (p->state == TASK_TRACED &&
(frozen(p->parent) ||
p->parent->state == TASK_STOPPED)) {
@@ -111,51 +110,76 @@ int freeze_processes(void)
continue;
}
if (is_user_space(p)) {
+ if (!freeze_user_space)
+ continue;
+
/* Freeze the task unless there is a vfork
* completion pending
*/
if (!p->vfork_done)
freeze_process(p);
- nr_user++;
} else {
- /* Freeze only if the user space is frozen */
- if (user_frozen)
- freeze_process(p);
- todo++;
+ if (freeze_user_space)
+ continue;
+
+ freeze_process(p);
}
+ todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
- todo += nr_user;
- if (!user_frozen && !nr_user) {
- sys_sync();
- start_time = jiffies;
- }
- user_frozen = !nr_user;
yield(); /* Yield is okay here */
- if (todo && time_after(jiffies, start_time + TIMEOUT))
+ if (todo && time_after(jiffies, end_time))
break;
- } while(todo);
+ } while (todo);
- /* This does not unfreeze processes that are already frozen
- * (we have slightly ugly calling convention in that respect,
- * and caller must call thaw_processes() if something fails),
- * but it cleans up leftover PF_FREEZE requests.
- */
if (todo) {
+ /* This does not unfreeze processes that are already frozen
+ * (we have slightly ugly calling convention in that respect,
+ * and caller must call thaw_processes() if something fails),
+ * but it cleans up leftover PF_FREEZE requests.
+ */
printk("\n");
- printk(KERN_ERR "Stopping tasks timed out "
- "after %d seconds (%d tasks remaining):\n",
- TIMEOUT / HZ, todo);
+ printk(KERN_ERR "Stopping %s timed out after %d seconds "
+ "(%d tasks refusing to freeze):\n",
+ freeze_user_space ? "user space processes" :
+ "kernel threads",
+ TIMEOUT / HZ, todo);
read_lock(&tasklist_lock);
do_each_thread(g, p) {
+ if (is_user_space(p) == !freeze_user_space)
+ continue;
+
if (freezeable(p) && !frozen(p))
printk(KERN_ERR " %s\n", p->comm);
+
cancel_freezing(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
- return todo;
}
+ return todo;
+}
+
+/**
+ * freeze_processes - tell processes to enter the refrigerator
+ *
+ * Returns 0 on success, or the number of processes that didn't freeze,
+ * although they were told to.
+ */
+int freeze_processes(void)
+{
+ unsigned int nr_unfrozen;
+
+ printk("Stopping tasks ... ");
+ nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE);
+ if (nr_unfrozen)
+ return nr_unfrozen;
+
+ sys_sync();
+ nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+ if (nr_unfrozen)
+ return nr_unfrozen;
+
printk("done.\n");
BUG_ON(in_atomic());
return 0;
-
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