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SubjectRe: Problem with freezable workqueues
Date
On Wednesday, 28 February 2007 21:08, Oleg Nesterov wrote:
> On 02/28, Rafael J. Wysocki wrote:
> >
> > On Wednesday, 28 February 2007 20:32, Oleg Nesterov wrote:
> > >
> > > I am sorry, I lost track of this problem. As for 2.6.21, create_freezeable_workqueue
> > > doesn't work and conflict with suspend. Why can't we remove it from XFS as you
> > > suggested before?
> >
> > Yes, we can (preparing a patch). I was just curious. :-)
>
> OK, thanks.
>
> We can (I think) do pretty much the same with some additional complications
> in worker_thread() (check !cpu_online() after try_to_freeze() and break).

Okay, but I've just finished the patch that removes the freezability of
workqueues (appended), so can we please do this in a separate one?

Rafael

---
Since freezable workqueues are broken in 2.6.21-rc
(cf. http://marc.theaimsgroup.com/?l=linux-kernel&m=116855740612755,
http://marc.theaimsgroup.com/?l=linux-kernel&m=117261312523921&w=2)
it's better to remove them altogether for 2.6.21 and change the only user of
them (XFS) accordingly.

---
fs/xfs/linux-2.6/xfs_buf.c | 4 ++--
include/linux/workqueue.h | 8 +++-----
kernel/workqueue.c | 21 +++++++--------------
3 files changed, 12 insertions(+), 21 deletions(-)

Index: linux-2.6.21-rc2/kernel/workqueue.c
===================================================================
--- linux-2.6.21-rc2.orig/kernel/workqueue.c
+++ linux-2.6.21-rc2/kernel/workqueue.c
@@ -59,7 +59,6 @@ struct cpu_workqueue_struct {

int run_depth; /* Detect run_workqueue() recursion depth */

- int freezeable; /* Freeze the thread during suspend */
} ____cacheline_aligned;

/*
@@ -352,8 +351,7 @@ static int worker_thread(void *__cwq)
struct k_sigaction sa;
sigset_t blocked;

- if (!cwq->freezeable)
- current->flags |= PF_NOFREEZE;
+ current->flags |= PF_NOFREEZE;

set_user_nice(current, -5);

@@ -376,9 +374,6 @@ 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();
@@ -454,8 +449,8 @@ void fastcall flush_workqueue(struct wor
}
EXPORT_SYMBOL_GPL(flush_workqueue);

-static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
- int cpu, int freezeable)
+static struct task_struct
+*create_workqueue_thread(struct workqueue_struct *wq, int cpu)
{
struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
struct task_struct *p;
@@ -465,7 +460,6 @@ static struct task_struct *create_workqu
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);
@@ -480,8 +474,7 @@ static struct task_struct *create_workqu
return p;
}

-struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread, int freezeable)
+struct workqueue_struct *__create_workqueue(const char *name, int singlethread)
{
int cpu, destroy = 0;
struct workqueue_struct *wq;
@@ -501,7 +494,7 @@ struct workqueue_struct *__create_workqu
mutex_lock(&workqueue_mutex);
if (singlethread) {
INIT_LIST_HEAD(&wq->list);
- p = create_workqueue_thread(wq, singlethread_cpu, freezeable);
+ p = create_workqueue_thread(wq, singlethread_cpu);
if (!p)
destroy = 1;
else
@@ -509,7 +502,7 @@ struct workqueue_struct *__create_workqu
} else {
list_add(&wq->list, &workqueues);
for_each_online_cpu(cpu) {
- p = create_workqueue_thread(wq, cpu, freezeable);
+ p = create_workqueue_thread(wq, cpu);
if (p) {
kthread_bind(p, cpu);
wake_up_process(p);
@@ -760,7 +753,7 @@ static int __devinit workqueue_cpu_callb
mutex_lock(&workqueue_mutex);
/* Create a new workqueue thread for it. */
list_for_each_entry(wq, &workqueues, list) {
- if (!create_workqueue_thread(wq, hotcpu, 0)) {
+ if (!create_workqueue_thread(wq, hotcpu)) {
printk("workqueue for %i failed\n", hotcpu);
return NOTIFY_BAD;
}
Index: linux-2.6.21-rc2/include/linux/workqueue.h
===================================================================
--- linux-2.6.21-rc2.orig/include/linux/workqueue.h
+++ linux-2.6.21-rc2/include/linux/workqueue.h
@@ -159,11 +159,9 @@ struct execute_work {


extern struct workqueue_struct *__create_workqueue(const char *name,
- 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)
+ int singlethread);
+#define create_workqueue(name) __create_workqueue((name), 0)
+#define create_singlethread_workqueue(name) __create_workqueue((name), 1)

extern void destroy_workqueue(struct workqueue_struct *wq);

Index: linux-2.6.21-rc2/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.21-rc2.orig/fs/xfs/linux-2.6/xfs_buf.c
+++ linux-2.6.21-rc2/fs/xfs/linux-2.6/xfs_buf.c
@@ -1829,11 +1829,11 @@ xfs_buf_init(void)
if (!xfs_buf_zone)
goto out_free_trace_buf;

- xfslogd_workqueue = create_freezeable_workqueue("xfslogd");
+ xfslogd_workqueue = create_workqueue("xfslogd");
if (!xfslogd_workqueue)
goto out_free_buf_zone;

- xfsdatad_workqueue = create_freezeable_workqueue("xfsdatad");
+ xfsdatad_workqueue = create_workqueue("xfsdatad");
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;

-
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