linux-kernel - Re: [PATCH] powerpc: silence a -Wcast-function-type warning in dawr_write_file

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Message-ID: <CA+7wUswMoeFdCBqnvMV6ZEbZShY2w23P5CMPktVavwYNL87_wQ@mail.gmail.com>
Date:   Wed, 15 May 2019 15:37:57 +0200
From:   Mathieu Malaterre <malat@...ian.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] powerpc: silence a -Wcast-function-type warning in dawr_write_file_bool

Hi Christoph,

On Wed, May 15, 2019 at 3:14 PM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Wed, May 15, 2019 at 02:09:42PM +0200, Mathieu Malaterre wrote:
> > In commit c1fe190c0672 ("powerpc: Add force enable of DAWR on P9
> > option") the following piece of code was added:
> >
> >    smp_call_function((smp_call_func_t)set_dawr, &null_brk, 0);
> >
> > Since GCC 8 this trigger the following warning about incompatible
> > function types:
>
> And the warning is there for a reason, and should not be hidden
> behind a cast.  This should instead be fixed by something like this:

<meme: I have no idea what I am doing>
OK, thanks for the quick feedback, will send a v2 asap.

> diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> index da307dd93ee3..a26b67a1be83 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -384,6 +384,12 @@ void hw_breakpoint_pmu_read(struct perf_event *bp)
>  bool dawr_force_enable;
>  EXPORT_SYMBOL_GPL(dawr_force_enable);
>
> +
> +static void set_dawr_cb(void *info)
> +{
> +       set_dawr(info);
> +}
> +
>  static ssize_t dawr_write_file_bool(struct file *file,
>                                     const char __user *user_buf,
>                                     size_t count, loff_t *ppos)
> @@ -403,7 +409,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
>
>         /* If we are clearing, make sure all CPUs have the DAWR cleared */
>         if (!dawr_force_enable)
> -               smp_call_function((smp_call_func_t)set_dawr, &null_brk, 0);
> +               smp_call_function(set_dawr_cb, &null_brk, 0);
>
>         return rc;
>  }