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Message-Id: <200611191301.56978.rjw@sisk.pl>
Date: Sun, 19 Nov 2006 13:01:56 +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 1/4] swsusp: Untangle thaw_processes
Hi,
On Sunday, 19 November 2006 03:04, Pavel Machek wrote:
> Hi!
>
> > Move the loop from thaw_processes() to a separate function and call it
> > independently for kernel threads and user space processes so that the order
> > of thawing tasks is clearly visible.
> >
> > Drop thaw_kernel_threads() which is never used.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > ---
> > include/linux/freezer.h | 6 -----
> > kernel/power/process.c | 55 +++++++++++++++++++++++++++---------------------
> > 2 files changed, 33 insertions(+), 28 deletions(-)
> >
> > Index: linux-2.6.19-rc5-mm2/include/linux/freezer.h
> > ===================================================================
> > --- linux-2.6.19-rc5-mm2.orig/include/linux/freezer.h
> > +++ linux-2.6.19-rc5-mm2/include/linux/freezer.h
> > @@ -1,8 +1,5 @@
> > /* Freezer declarations */
> >
> > -#define FREEZER_KERNEL_THREADS 0
> > -#define FREEZER_ALL_THREADS 1
> > -
> > #ifdef CONFIG_PM
> > /*
> > * Check if a process has been frozen
> > @@ -60,8 +57,7 @@ static inline void frozen_process(struct
> >
> > extern void refrigerator(void);
> > extern int freeze_processes(void);
> > -#define thaw_processes() do { thaw_some_processes(FREEZER_ALL_THREADS); } while(0)
> > -#define thaw_kernel_threads() do { thaw_some_processes(FREEZER_KERNEL_THREADS); } while(0)
> > +extern void thaw_processes(void);
> >
> > static inline int try_to_freeze(void)
> > {
> > 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
> > @@ -20,6 +20,8 @@
> > */
> > #define TIMEOUT (20 * HZ)
> >
> > +#define FREEZER_KERNEL_THREADS 0
> > +#define FREEZER_USER_SPACE 1
>
> The variable is named "is_user_space"... so maybe the defines are not
> strictly needed?
Not strlctly, but if I see
thaw_tasks(FREEZER_KERNEL_THREADS);
thaw_tasks(FREEZER_USER_SPACE);
I can figure out what's going on even without looking at thaw_tasks().
> > + do_each_thread(g, p) {
> > + if (!freezeable(p))
> > + continue;
> >
> > + if (is_user_space(p)) {
> > + if (!thaw_user_space)
> > + continue;
> > + } else {
> > + if (thaw_user_space)
> > + continue;
> > + }
>
> if (is_user_space(p) != thaw_user_space)
> continue;
Ah, good idea. In fact I prefer if (is_user_space(p) == !thaw_user_space),
because it will work even if thaw_user_space is different to 1 and 0.
Revised patch follows.
---
Move the loop from thaw_processes() to a separate function and call it
independently for kernel threads and user space processes so that the order
of thawing tasks is clearly visible.
Drop thaw_kernel_threads() which is never used.
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
include/linux/freezer.h | 6 -----
kernel/power/process.c | 53 ++++++++++++++++++++++++++----------------------
2 files changed, 30 insertions(+), 29 deletions(-)
Index: linux-2.6.19-rc5-mm2/include/linux/freezer.h
===================================================================
--- linux-2.6.19-rc5-mm2.orig/include/linux/freezer.h
+++ linux-2.6.19-rc5-mm2/include/linux/freezer.h
@@ -1,8 +1,5 @@
/* Freezer declarations */
-#define FREEZER_KERNEL_THREADS 0
-#define FREEZER_ALL_THREADS 1
-
#ifdef CONFIG_PM
/*
* Check if a process has been frozen
@@ -60,8 +57,7 @@ static inline void frozen_process(struct
extern void refrigerator(void);
extern int freeze_processes(void);
-#define thaw_processes() do { thaw_some_processes(FREEZER_ALL_THREADS); } while(0)
-#define thaw_kernel_threads() do { thaw_some_processes(FREEZER_KERNEL_THREADS); } while(0)
+extern void thaw_processes(void);
static inline int try_to_freeze(void)
{
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
@@ -20,6 +20,8 @@
*/
#define TIMEOUT (20 * HZ)
+#define FREEZER_KERNEL_THREADS 0
+#define FREEZER_USER_SPACE 1
static inline int freezeable(struct task_struct * p)
{
@@ -79,6 +81,11 @@ static void cancel_freezing(struct task_
}
}
+static inline int is_user_space(struct task_struct *p)
+{
+ return p->mm && !(p->flags & PF_BORROWED_MM);
+}
+
/* 0 = success, else # of processes that we failed to stop */
int freeze_processes(void)
{
@@ -103,10 +110,9 @@ int freeze_processes(void)
cancel_freezing(p);
continue;
}
- if (p->mm && !(p->flags & PF_BORROWED_MM)) {
- /* The task is a user-space one.
- * Freeze it unless there's a vfork completion
- * pending
+ if (is_user_space(p)) {
+ /* Freeze the task unless there is a vfork
+ * completion pending
*/
if (!p->vfork_done)
freeze_process(p);
@@ -155,31 +161,30 @@ int freeze_processes(void)
return 0;
}
-void thaw_some_processes(int all)
+static void thaw_tasks(int thaw_user_space)
{
struct task_struct *g, *p;
- int pass = 0; /* Pass 0 = Kernel space, 1 = Userspace */
- printk("Restarting tasks... ");
read_lock(&tasklist_lock);
- do {
- do_each_thread(g, p) {
- /*
- * is_user = 0 if kernel thread or borrowed mm,
- * 1 otherwise.
- */
- int is_user = !!(p->mm && !(p->flags & PF_BORROWED_MM));
- if (!freezeable(p) || (is_user != pass))
- continue;
- if (!thaw_process(p))
- printk(KERN_INFO
- "Strange, %s not stopped\n", p->comm);
- } while_each_thread(g, p);
-
- pass++;
- } while (pass < 2 && all);
-
+ do_each_thread(g, p) {
+ if (!freezeable(p))
+ continue;
+
+ if (is_user_space(p) == !thaw_user_space)
+ continue;
+
+ if (!thaw_process(p))
+ printk(KERN_WARNING " Strange, %s not stopped\n",
+ p->comm );
+ } while_each_thread(g, p);
read_unlock(&tasklist_lock);
+}
+
+void thaw_processes(void)
+{
+ printk("Restarting tasks ... ");
+ thaw_tasks(FREEZER_KERNEL_THREADS);
+ thaw_tasks(FREEZER_USER_SPACE);
schedule();
printk("done.\n");
}
-
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