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Date:   Wed, 26 Feb 2020 10:01:02 +0100
From:   Greg Kurz <groug@kaod.org>
To:     "Alastair D'Silva" <alastair@d-silva.org>
Cc:     "'Baoquan He'" <bhe@redhat.com>,
        "'Alastair D'Silva'" <alastair@au1.ibm.com>,
        "'Aneesh Kumar K . V'" <aneesh.kumar@linux.ibm.com>,
        "'Oliver O'Halloran'" <oohall@gmail.com>,
        "'Benjamin Herrenschmidt'" <benh@kernel.crashing.org>,
        "'Paul Mackerras'" <paulus@samba.org>,
        "'Michael Ellerman'" <mpe@ellerman.id.au>,
        "'Frederic Barrat'" <fbarrat@linux.ibm.com>,
        "'Andrew Donnellan'" <ajd@linux.ibm.com>,
        "'Arnd Bergmann'" <arnd@arndb.de>,
        "'Greg Kroah-Hartman'" <gregkh@linuxfoundation.org>,
        "'Dan Williams'" <dan.j.williams@intel.com>,
        "'Vishal Verma'" <vishal.l.verma@intel.com>,
        "'Dave Jiang'" <dave.jiang@intel.com>,
        "'Ira Weiny'" <ira.weiny@intel.com>,
        "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'Mauro Carvalho Chehab'" <mchehab+samsung@kernel.org>,
        "'David S. Miller'" <davem@davemloft.net>,
        "'Rob Herring'" <robh@kernel.org>,
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        "'Krzysztof Kozlowski'" <krzk@kernel.org>,
        "'Mahesh Salgaonkar'" <mahesh@linux.vnet.ibm.com>,
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        "'Anju T Sudhakar'" <anju@linux.vnet.ibm.com>,
        "'Hari Bathini'" <hbathini@linux.ibm.com>,
        "'Thomas Gleixner'" <tglx@linutronix.de>,
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Subject: Re: [PATCH v3 04/27] ocxl: Remove unnecessary externs
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On Wed, 26 Feb 2020 19:26:34 +1100
"Alastair D'Silva" <alastair@d-silva.org> wrote:

> > -----Original Message-----
> > From: Baoquan He <bhe@redhat.com>
> > Sent: Wednesday, 26 February 2020 7:15 PM
> > To: Alastair D'Silva <alastair@au1.ibm.com>
> > Cc: alastair@d-silva.org; Aneesh Kumar K . V
> > <aneesh.kumar@linux.ibm.com>; Oliver O'Halloran <oohall@gmail.com>;
> > Benjamin Herrenschmidt <benh@kernel.crashing.org>; Paul Mackerras
> > <paulus@samba.org>; Michael Ellerman <mpe@ellerman.id.au>; Frederic
> > Barrat <fbarrat@linux.ibm.com>; Andrew Donnellan <ajd@linux.ibm.com>;
> > Arnd Bergmann <arnd@arndb.de>; Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org>; Dan Williams <dan.j.williams@intel.com>;
> > Vishal Verma <vishal.l.verma@intel.com>; Dave Jiang
> > <dave.jiang@intel.com>; Ira Weiny <ira.weiny@intel.com>; Andrew Morton
> > <akpm@linux-foundation.org>; Mauro Carvalho Chehab
> > <mchehab+samsung@kernel.org>; David S. Miller <davem@davemloft.net>;
> > Rob Herring <robh@kernel.org>; Anton Blanchard <anton@ozlabs.org>;
> > Krzysztof Kozlowski <krzk@kernel.org>; Mahesh Salgaonkar
> > <mahesh@linux.vnet.ibm.com>; Madhavan Srinivasan
> > <maddy@linux.vnet.ibm.com>; Cédric Le Goater <clg@kaod.org>; Anju T
> > Sudhakar <anju@linux.vnet.ibm.com>; Hari Bathini
> > <hbathini@linux.ibm.com>; Thomas Gleixner <tglx@linutronix.de>; Greg
> > Kurz <groug@kaod.org>; Nicholas Piggin <npiggin@gmail.com>; Masahiro
> > Yamada <yamada.masahiro@socionext.com>; Alexey Kardashevskiy
> > <aik@ozlabs.ru>; linux-kernel@vger.kernel.org; linuxppc-
> > dev@lists.ozlabs.org; linux-nvdimm@lists.01.org; linux-mm@kvack.org
> > Subject: Re: [PATCH v3 04/27] ocxl: Remove unnecessary externs
> > 
> > On 02/21/20 at 02:26pm, Alastair D'Silva wrote:
> > > From: Alastair D'Silva <alastair@d-silva.org>
> > >
> > > Function declarations don't need externs, remove the existing ones so
> > > they are consistent with newer code
> > >
> > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > ---
> > >  arch/powerpc/include/asm/pnv-ocxl.h | 32 ++++++++++++++---------------
> > >  include/misc/ocxl.h                 |  6 +++---
> > >  2 files changed, 18 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/arch/powerpc/include/asm/pnv-ocxl.h
> > > b/arch/powerpc/include/asm/pnv-ocxl.h
> > > index 0b2a6707e555..b23c99bc0c84 100644
> > > --- a/arch/powerpc/include/asm/pnv-ocxl.h
> > > +++ b/arch/powerpc/include/asm/pnv-ocxl.h
> > > @@ -9,29 +9,27 @@
> > >  #define PNV_OCXL_TL_BITS_PER_RATE       4
> > >  #define PNV_OCXL_TL_RATE_BUF_SIZE
> > ((PNV_OCXL_TL_MAX_TEMPLATE+1) * PNV_OCXL_TL_BITS_PER_RATE / 8)
> > >
> > > -extern int pnv_ocxl_get_actag(struct pci_dev *dev, u16 *base, u16
> > *enabled,
> > > -			u16 *supported);
> > 
> > It works w or w/o extern when declare functions. Searching 'extern'
> > under include can find so many functions with 'extern' adding. Do we have
> a
> > explicit standard if we should add or remove 'exter' in function
> declaration?
> > 
> > I have no objection to this patch, just want to make clear so that I can
> handle
> > it w/o confusion.
> > 
> > Thanks
> > Baoquan
> > 
> 
> For the OpenCAPI driver, we have settled on not having 'extern' on
> functions.
> 
> I don't think I've seen a standard that supports or refutes this, but it
> does not value add.
> 

FWIW this is a warning condition for checkpatch:

$ ./scripts/checkpatch.pl --strict -f include/misc/ocxl.h

[...]

CHECK: extern prototypes should be avoided in .h files
#176: FILE: include/misc/ocxl.h:176:
+extern int ocxl_afu_irq_alloc(struct ocxl_context *ctx, int *irq_id);

[...]