linux-kernel - Re: [PATCH 2/2] drm/xe/configfs: fix clang warnings for missing parameter name

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Message-ID: <qgugikjwzoc2ia7no5x5jspgu6dx6p6yeuhpxkqfsdggxtk5ty@ptmw53oycmnk>
Date: Tue, 21 Oct 2025 09:47:36 -0700
From: Ryan Neph <ryanneph@...gle.com>
To: Nathan Chancellor <nathan@...nel.org>
Cc: David Laight <david.laight.linux@...il.com>, 
	Lucas De Marchi <lucas.demarchi@...el.com>, 
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, intel-xe@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/xe/configfs: fix clang warnings for missing
 parameter name

On Tue, Oct 21, 2025 at 08:39:57AM +0200, Nathan Chancellor wrote:
> On Mon, Oct 20, 2025 at 11:05:13AM +0100, David Laight wrote:
> > On Fri, 17 Oct 2025 12:46:26 -0700
> > Ryan Neph <ryanneph@...gle.com> wrote:
> > 
> > > Fixes warning from clang-17 that look like:
> > > 
> > > drivers/gpu/drm/xe/xe_configfs.h:35:97: error: omitting the parameter name in a function definition is a C2x extension [-Werror,-Wc2x-extensions]
> > >    35 | static inline u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev, enum xe_engine_class,
> > 
> > Why did that become invalid?
> > It has pretty much always been used - and can be used to avoid -Wshadow warnings.
> > This looks like a clang bug.
> > And you'd want a specific -W 'knob' for it as well.
> > 
> > At a guess the C2x extension lets the name be omitted in the function body for
> > an unused parameter (the same as C++).
> > I think that is the 'definition' and the ones being changed here are the 'declaration'.
> > But I might be wrong.
> 
> I don't think you read the patch clearly enough. Both declarations and
> 'static inline' definitions are being updated in this patch, likely for
> consistency rather than necessity (but the commit message could call
> this out). I don't see how there is a clang bug here.

Correct. The warning is generated for the stub definitions on the false branch of the
`#if IS_ENABLED(CONFIG_CONFIGFS_FS)`.

The pure declarations on the true side of the branch don't need a named variable but I included them for
consistency. I can mention this in the commit message for v2 if desired.

> 
> > > 
> > > Signed-off-by: Ryan Neph <ryanneph@...gle.com>
> > > ---
> > >  drivers/gpu/drm/xe/xe_configfs.h | 10 ++++++----
> > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/xe/xe_configfs.h b/drivers/gpu/drm/xe/xe_configfs.h
> > > index fed57be0b90e146d57d966bab0e55e1723513997..a0d614b37efd54b89390f04a238aef1a8d4df4e2 100644
> > > --- a/drivers/gpu/drm/xe/xe_configfs.h
> > > +++ b/drivers/gpu/drm/xe/xe_configfs.h
> > > @@ -21,9 +21,9 @@ bool xe_configfs_primary_gt_allowed(struct pci_dev *pdev);
> > >  bool xe_configfs_media_gt_allowed(struct pci_dev *pdev);
> > >  u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev);
> > >  bool xe_configfs_get_psmi_enabled(struct pci_dev *pdev);
> > > -u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev, enum xe_engine_class,
> > > +u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev, enum xe_engine_class class,
> > >  				       const u32 **cs);
> > > -u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev, enum xe_engine_class,
> > > +u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev, enum xe_engine_class class,
> > >  					const u32 **cs);
> > >  #ifdef CONFIG_PCI_IOV
> > >  unsigned int xe_configfs_get_max_vfs(struct pci_dev *pdev);
> > > @@ -37,9 +37,11 @@ static inline bool xe_configfs_primary_gt_allowed(struct pci_dev *pdev) { return
> > >  static inline bool xe_configfs_media_gt_allowed(struct pci_dev *pdev) { return true; }
> > >  static inline u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev) { return U64_MAX; }
> > >  static inline bool xe_configfs_get_psmi_enabled(struct pci_dev *pdev) { return false; }
> > > -static inline u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev, enum xe_engine_class,
> > > +static inline u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
> > > +						     enum xe_engine_class class,
> > >  						     const u32 **cs) { return 0; }
> > > -static inline u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev, enum xe_engine_class,
> > > +static inline u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
> > > +						      enum xe_engine_class class,
> > >  						      const u32 **cs) { return 0; }
> > >  static inline unsigned int xe_configfs_get_max_vfs(struct pci_dev *pdev) { return UINT_MAX; }
> > >  #endif
> > > 
> >