[PATCH] Support for freezeable workqueues

Make it possible to create a workqueue the worker thread of which will be
frozen during suspend, along with other kernel threads.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>
Cc: David Chinner <dgc@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 19 insertions, 9 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 4a3ea83c6d16..f0cb1df7b475 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -147,9 +147,11 @@ struct execute_work {
 
 
 extern struct workqueue_struct *__create_workqueue(const char *name,
-                                                    int singlethread);
-#define create_workqueue(name) __create_workqueue((name), 0)
-#define create_singlethread_workqueue(name) __create_workqueue((name), 1)
+                                                    int singlethread,
+                                                    int freezeable);
+#define create_workqueue(name) __create_workqueue((name), 0, 0)
+#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
+#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
 
 extern void destroy_workqueue(struct workqueue_struct *wq);
 
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8d1e7cb8a51a..2945b094d871 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -29,6 +29,7 @@
 #include <linux/kthread.h>
 #include <linux/hardirq.h>
 #include <linux/mempolicy.h>
+#include <linux/freezer.h>
 
 /*
  * The per-CPU workqueue (if single thread, we always use the first
@@ -55,6 +56,8 @@ struct cpu_workqueue_struct {
         struct task_struct *thread;
 
         int run_depth;          /* Detect run_workqueue() recursion depth */
+
+        int freezeable;         /* Freeze the thread during suspend */
 } ____cacheline_aligned;
 
 /*
@@ -265,7 +268,8 @@ static int worker_thread(void *__cwq)
         struct k_sigaction sa;
         sigset_t blocked;
 
-        current->flags |= PF_NOFREEZE;
+        if (!cwq->freezeable)
+                current->flags |= PF_NOFREEZE;
 
         set_user_nice(current, -5);
 
@@ -288,6 +292,9 @@ static int worker_thread(void *__cwq)
 
         set_current_state(TASK_INTERRUPTIBLE);
         while (!kthread_should_stop()) {
+                if (cwq->freezeable)
+                        try_to_freeze();
+
                 add_wait_queue(&cwq->more_work, &wait);
                 if (list_empty(&cwq->worklist))
                         schedule();
@@ -364,7 +371,7 @@ void fastcall flush_workqueue(struct workqueue_struct *wq)
 EXPORT_SYMBOL_GPL(flush_workqueue);
 
 static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
-                                                   int cpu)
+                                                   int cpu, int freezeable)
 {
         struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
         struct task_struct *p;
@@ -374,6 +381,7 @@ static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
         cwq->thread = NULL;
         cwq->insert_sequence = 0;
         cwq->remove_sequence = 0;
+        cwq->freezeable = freezeable;
         INIT_LIST_HEAD(&cwq->worklist);
         init_waitqueue_head(&cwq->more_work);
         init_waitqueue_head(&cwq->work_done);
@@ -389,7 +397,7 @@ static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
 }
 
 struct workqueue_struct *__create_workqueue(const char *name,
-                                            int singlethread)
+                                            int singlethread, int freezeable)
 {
         int cpu, destroy = 0;
         struct workqueue_struct *wq;
@@ -409,7 +417,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
         mutex_lock(&workqueue_mutex);
         if (singlethread) {
                 INIT_LIST_HEAD(&wq->list);
-                p = create_workqueue_thread(wq, singlethread_cpu);
+                p = create_workqueue_thread(wq, singlethread_cpu, freezeable);
                 if (!p)
                         destroy = 1;
                 else
@@ -417,7 +425,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
         } else {
                 list_add(&wq->list, &workqueues);
                 for_each_online_cpu(cpu) {
-                        p = create_workqueue_thread(wq, cpu);
+                        p = create_workqueue_thread(wq, cpu, freezeable);
                         if (p) {
                                 kthread_bind(p, cpu);
                                 wake_up_process(p);
@@ -667,7 +675,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
                 mutex_lock(&workqueue_mutex);
                 /* Create a new workqueue thread for it. */
                 list_for_each_entry(wq, &workqueues, list) {
-                        if (!create_workqueue_thread(wq, hotcpu)) {
+                        if (!create_workqueue_thread(wq, hotcpu, 0)) {
                                 printk("workqueue for %i failed\n", hotcpu);
                                 return NOTIFY_BAD;
                         }