linux-kernel - Re: [PATCH V2 3/9] fork: move PF_IO_WORKER's kernel frame setup to new flag

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Message-ID: <20210922123944.qo3quonmrz2fv2bb@wittgenstein>
Date:   Wed, 22 Sep 2021 14:39:44 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Mike Christie <michael.christie@...cle.com>, hdanton@...a.com,
        Christoph Hellwig <hch@...radead.org>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Stefano Garzarella --cc virtualization @ lists . linux-foundation . org" 
        <sgarzare@...hat.com>, virtualization@...ts.linux-foundation.org,
        Jens Axboe <axboe@...nel.dk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 3/9] fork: move PF_IO_WORKER's kernel frame setup to
 new flag

On Wed, Sep 22, 2021 at 02:32:37PM +0200, Geert Uytterhoeven wrote:
> Hi Mike,
> 
> On Tue, Sep 21, 2021 at 11:55 PM Mike Christie
> <michael.christie@...cle.com> wrote:
> > The vhost worker threads need the same frame setup as io_uring's worker
> > threads, but handle signals differently and do not need the same
> > scheduling behavior. This patch separate's the frame setup parts of
> > PF_IO_WORKER into a kernel_clone_args flag, KERN_WORKER_USER.
> >
> > Signed-off-by: Mike Christie <michael.christie@...cle.com>
> 
> Thanks for your patch!
> 
> > --- a/arch/m68k/kernel/process.c
> > +++ b/arch/m68k/kernel/process.c
> > @@ -157,7 +157,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
> >          */
> >         p->thread.fs = get_fs().seg;
> >
> > -       if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
> > +       if (unlikely(p->flags & (PF_KTHREAD) ||
> > +                    worker_flags & KERN_WORKER_USER)) {
> 
> I guess it wouldn't hurt to add parentheses to improve
> readability:
> 
>     if (unlikely((p->flags & (PF_KTHREAD)) ||
>                  (worker_flags & KERN_WORKER_USER))) {

Yep, I stumbled over the same thing!