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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 12 May 2021 13:32:21 +0200
Message-ID: <CAJZ5v0gbRb+CGEV2D09KqhiRPPWxPBtXmwrp5iyuB-xTBEBfvA@mail.gmail.com>
Subject: Re: Qestion about device link
To:     Hillf Danton <hdanton@sina.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Saravana Kannan <saravanak@google.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "chenxiang (M)" <chenxiang66@hisilicon.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        John Garry <john.garry@huawei.com>,
        "scsi list : TARGET SUBSYSTEM" <linux-scsi@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Wed, May 12, 2021 at 8:38 AM Hillf Danton <hdanton@sina.com> wrote:
>
> On Tue, 11 May 2021 21:43:40 Rafael J. Wysocki  wrote:
> > >  #ifdef CONFIG_SRCU
> > > +static void __device_link_free_fn(struct work_struct *work)
> > > +{
> > > +       device_link_free(container_of(work, struct device_link, srcu.work));
> > > +}
> > > +
> > >  static void __device_link_free_srcu(struct rcu_head *rhead)
> > >  {
> > > -       device_link_free(container_of(rhead, struct device_link, rcu_head));
> > > +       struct device_link *link = container_of(rhead, struct device_link,
> > > +                                               srcu.rhead);
> > > +       struct work_struct *work = &link->srcu.work;
> > > +
> > > +       /*
> > > +        * Because device_link_free() may sleep in some cases, schedule the
> > > +        * execution of it instead of invoking it directly.
> > > +        */
> > > +       INIT_WORK(work, __device_link_free_fn);
> > > +       schedule_work(work);
> > >  }
>
> Nope, you need something like queue_work(system_unbound_wq, work); instead
> because of the blocking wq callback.

system_long_wq rather, as it really doesn't matter when it gets completed.