Hello Thierry,
On Mon, Oct 30, 2023 at 4:30 PM Thierry Reding <thierry.reding@xxxxxxxxx> wrote:
>
> On Wed, Oct 25, 2023 at 07:25:50PM +0800, Baolu Lu wrote:
> > On 2023/10/25 19:01, Dario Binacchi wrote:
> > > The return value of debugfs_create_dir() should be checked using the
> > > IS_ERR() function.
> > >
> > > Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
> > > ---
> > >
> > > drivers/iommu/tegra-smmu.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> > > index e445f80d0226..cd1d80c4c673 100644
> > > --- a/drivers/iommu/tegra-smmu.c
> > > +++ b/drivers/iommu/tegra-smmu.c
> > > @@ -1056,7 +1056,7 @@ DEFINE_SHOW_ATTRIBUTE(tegra_smmu_clients);
> > > static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
> > > {
> > > smmu->debugfs = debugfs_create_dir("smmu", NULL);
> > > - if (!smmu->debugfs)
> > > + if (IS_ERR(smmu->debugfs))
> > > return;
> >
> > This check can be removed, as debugfs_create_file() can handle the case
> > where @parent is an error pointer.
>
> A patch for this has been in linux-next for a few weeks, see:
>
> commit f7da9c081517daba70f9f9342e09d7a6322ba323
> Author: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
> Date: Fri Sep 1 15:30:56 2023 +0800
>
> iommu/tegra-smmu: Drop unnecessary error check for for debugfs_create_dir()
>
> The debugfs_create_dir() function returns error pointers.
> It never returns NULL.
>
> As Baolu suggested, this patch removes the error checking for
> debugfs_create_dir in tegra-smmu.c. This is because the DebugFS kernel API
> is developed in a way that the caller can safely ignore the errors that
> occur during the creation of DebugFS nodes. The debugfs APIs have
> a IS_ERR() judge in start_creating() which can handle it gracefully. So
> these checks are unnecessary.
>
> Fixes: d1313e7896e9 ("iommu/tegra-smmu: Add debugfs support")
> Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
> Suggested-by: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> Acked-by: Thierry Reding <treding@xxxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20230901073056.1364755-1-ruanjinjie@xxxxxxxxxx
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
>
Thanks for the explanation,
regards
Dario
> Thierry
--
Dario Binacchi
Senior Embedded Linux Developer
dario.binacchi@xxxxxxxxxxxxxxxxxxxx
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