[PATCH] swsusp: Untangle freeze_processes

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@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/power/process.c b/kernel/power/process.c
index fd0ebb942f5097495e493b79527da5b7c87f74d4..99eeb119b06db1d350d04de044fdb624f4627a19 100644 (file)
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -86,24 +86,23 @@ 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)
+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;