linux-kernel - Re: [PATCH] kernel/reboot: add devm_register_reboot

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Date:   Thu, 30 Mar 2017 16:24:16 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Andrey Smirnov <andrew.smirnov@...il.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Chris Healy <cphealy@...il.com>
Subject: Re: [PATCH] kernel/reboot: add devm_register_reboot_notifier

On Thu, 30 Mar 2017 15:55:43 -0700 Andrey Smirnov <andrew.smirnov@...il.com> wrote:

> On Wed, Mar 29, 2017 at 4:17 PM, Andrew Morton
> <akpm@...ux-foundation.org> wrote:
> > On Mon, 20 Mar 2017 10:17:53 -0700 Andrey Smirnov <andrew.smirnov@...il.com> wrote:
> >
> >> Add devm_* wrapper around register_reboot_notifier to simplify device
> >> specific reboot notifier registration/unregistration.
> >>
> >> --- a/kernel/reboot.c
> >> +++ b/kernel/reboot.c
> >> @@ -104,6 +104,33 @@ int unregister_reboot_notifier(struct notifier_block *nb)
> >>  }
> >>  EXPORT_SYMBOL(unregister_reboot_notifier);
> >>
> >> +static void devm_unregister_reboot_notifier(struct device *dev, void *res)
> >> +{
> >> +     WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
> >> +}
> >> +
> >> +int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
> >> +{
> >> +     struct notifier_block **rcnb;
> >> +     int ret;
> >> +
> >> +     rcnb = devres_alloc(devm_unregister_reboot_notifier,
> >> +                         sizeof(*rcnb), GFP_KERNEL);
> >> +     if (!rcnb)
> >> +             return -ENOMEM;
> >> +
> >> +     ret = register_reboot_notifier(nb);
> >> +     if (!ret) {
> >> +             *rcnb = nb;
> >> +             devres_add(dev, rcnb);
> >> +     } else {
> >> +             devres_free(rcnb);
> >> +     }
> >> +
> >> +     return ret;
> >> +}
> >> +EXPORT_SYMBOL(devm_register_reboot_notifier);
> >
> > Seems reasonable.  Can we please have some patches which actually use
> > this?
> 
> I will be submitting a serdev/watchdog driver in next couple of weeks,
> I can CC you on that thread.

It would be nice to convert some other call sites as well, please - at
least to get additional test coverage and to demonstrate the usefulness
of the new interface.