linux-kernel - Re: [PATCH v3 02/10] ata: pata_platform: Drop use of unlikely() in pata_platform

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Date:   Sun, 26 Dec 2021 14:21:48 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     Sergey Shtylyov <s.shtylyov@....ru>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Rob Herring <robh+dt@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" 
        <linux-ide@...r.kernel.org>
Subject: Re: [PATCH v3 02/10] ata: pata_platform: Drop use of unlikely() in pata_platform_probe

Hi Damien,

On Sun, Dec 26, 2021 at 11:56 AM Damien Le Moal
<damien.lemoal@...nsource.wdc.com> wrote:
>
> On 12/25/21 03:02, Lad, Prabhakar wrote:
> > Hi Sergey,
> >
> > Thank you for the review.
> >
> > On Fri, Dec 24, 2021 at 5:54 PM Sergey Shtylyov <s.shtylyov@....ru> wrote:
> >>
> >> On 12/24/21 4:12 PM, Lad Prabhakar wrote:
> >>
> >>> pata_platform_probe() isn't a hotpath, which makes it's questionable to
> >>> use unlikely(). Therefore let's simply drop it.
> >>>
> >>> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >>> ---
> >>> v2-->v3
> >>> * New patch
> >>> ---
> >>>  drivers/ata/pata_platform.c | 4 ++--
> >>>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/ata/pata_platform.c b/drivers/ata/pata_platform.c
> >>> index cb3134bf88eb..29902001e223 100644
> >>> --- a/drivers/ata/pata_platform.c
> >>> +++ b/drivers/ata/pata_platform.c
> >>> @@ -199,14 +199,14 @@ static int pata_platform_probe(struct platform_device *pdev)
> >>>        * Get the I/O base first
> >>>        */
> >>>       io_res = platform_get_mem_or_io(pdev, 0);
> >>> -     if (unlikely(!io_res))
> >>> +     if (!io_res)
> >>>               return -EINVAL;
> >>>
> >>>       /*
> >>>        * Then the CTL base
> >>>        */
> >>>       ctl_res = platform_get_mem_or_io(pdev, 1);
> >>> -     if (unlikely(!ctl_res))
> >>> +     if (!ctl_res)
> >>>               return -EINVAL;
> >>
> >>    I think you should combine this with patch #1.
> >>
> > I'd like to keep the changes separate from patch #1, as it's unrelated.
>
> But your patch 1 adds the unlikely... So simply do not add it in patch
> one and this patch is not necessary anymore.
>
patch #1 just replaces two platform_get_resource() with one
platform_get_mem_or_io() call, the unlikely() is just indented towards
the left. But anyway I can merge this into #1.

Are you OK with the rest of the patches?

Cheers,
Prabhakar