Re: [Patch] Per kthread freezer flags

[Pavel Machek <pavel@ucw.cz>]

Hi!

> At the moment, all kthreads have PF_NOFREEZE set, meaning that they're
> not refrigerated during a suspend. This isn't right for some threads.

Looks good, but see comments below.



> --- linux-2.6.8-rc1-mm1/drivers/block/pktcdvd.c	2004-07-28 16:37:46.000000000 +1000
> +++ linux-2.6.8-rc1-mm1-kthread_refrigerator/drivers/block/pktcdvd.c	2004-07-28 16:59:22.000000000 +1000
> @@ -2372,7 +2372,7 @@
>  
>  	pkt_init_queue(pd);
>  
> -	pd->cdrw.thread = kthread_run(kcdrwd, pd, "%s", pd->name);
> +	pd->cdrw.thread = kthread_run(kcdrwd, pd, "%s", 0, pd->name);
>  	if (IS_ERR(pd->cdrw.thread)) {
>  		printk("pktcdvd: can't start kernel thread\n");
>  		ret = -ENOMEM;

What if someone does swapon /dev/pktdvd0?


> +++ linux-2.6.8-rc1-mm1-kthread_refrigerator/drivers/md/dm-raid1.c	2004-07-28 16:48:44.000000000 +1000
> @@ -1238,7 +1238,7 @@
>  	if (r)
>  		return r;
>  
> -	_kmirrord_wq = create_workqueue("kmirrord");
> +	_kmirrord_wq = create_workqueue("kmirrord", PF_NOFREEZE);
>  	if (!_kmirrord_wq) {
>  		DMERR("couldn't start kmirrord");
>  		dm_dirty_log_exit();


I'm not 100% certain what kmirrord does, but we certainly do not
want raid array to be reconstructed while suspending.



linux-2.6.8-rc1-mm1-kthread_refrigerator/fs/aio.c
> --- linux-2.6.8-rc1-mm1/fs/aio.c	2004-07-28 16:36:03.000000000 +1000
> +++ linux-2.6.8-rc1-mm1-kthread_refrigerator/fs/aio.c	2004-07-28 16:43:48.000000000 +1000
> @@ -69,7 +69,7 @@
>  	kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
>  				0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
>  
> -	aio_wq = create_workqueue("aio");
> +	aio_wq = create_workqueue("aio", PF_NOFREEZE);
>  
>  	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
>  

Are you sure? Unless swsusp itself uses aio, we want this to freeze.


linux-2.6.8-rc1-mm1-kthread_refrigerator/kernel/sched.c	2004-07-28 16:43:48.000000000 +1000
> @@ -3550,7 +3550,8 @@
>  
>  	switch (action) {
>  	case CPU_UP_PREPARE:
> -		p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
> +		p = kthread_create(migration_thread, hcpu, 0,
> +				"migration/%d",cpu);
>  		if (IS_ERR(p))
>  			return NOTIFY_BAD;
>  		p->flags |= PF_NOFREEZE;

Ugh, creating thread normally only to add PF_NOFREEZE 2 lines later
looks bad.

> +++ linux-2.6.8-rc1-mm1-kthread_refrigerator/kernel/softirq.c	2004-07-28 16:43:48.000000000 +1000
> @@ -425,7 +425,7 @@
>  	case CPU_UP_PREPARE:
>  		BUG_ON(per_cpu(tasklet_vec, hotcpu).list);
>  		BUG_ON(per_cpu(tasklet_hi_vec, hotcpu).list);
> -		p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu);
> +		p = kthread_create(ksoftirqd, hcpu, 0, "ksoftirqd/%d", hotcpu);
>  		if (IS_ERR(p)) {
>  			printk("ksoftirqd for %i failed\n", hotcpu);
>  			return NOTIFY_BAD;

I guess softinterrupts may be neccessary for suspend... Random drivers may use
them, right?


				Pavel
-- 
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