kthread: Don't abuse kthread_create_on_cpu() in __kthread_create_worker()
authorOleg Nesterov <oleg@redhat.com>
Tue, 29 Nov 2016 17:51:10 +0000 (18:51 +0100)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 8 Dec 2016 13:36:20 +0000 (14:36 +0100)
commit8fb9dcbdc3619741c10c573199d804161c34c89a
tree30ae9a0c9fb46b026361d7b74162cc746da08d2c
parentcf380a4a96e2260742051fa7fc831596bb26cc8b
kthread: Don't abuse kthread_create_on_cpu() in __kthread_create_worker()

kthread_create_on_cpu() sets KTHREAD_IS_PER_CPU and kthread->cpu, this
only makes sense if this kthread can be parked/unparked by cpuhp code.
kthread workers never call kthread_parkme() so this has no effect.

Change __kthread_create_worker() to simply call kthread_bind(task, cpu).
The very fact that kthread_create_on_cpu() doesn't accept a generic fmt
shows that it should not be used outside of smpboot.c.

Now, the only reason we can not unexport this helper and move it into
smpboot.c is that it sets kthread->cpu and struct kthread is not exported.
And the only reason we can not kill kthread->cpu is that kthread_unpark()
is used by drivers/gpu/drm/amd/scheduler/gpu_scheduler.c and thus we can
not turn _unpark into kthread_unpark(struct smp_hotplug_thread *, cpu).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Chunming Zhou <David1.Zhou@amd.com>
Cc: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20161129175110.GA5342@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kernel/kthread.c