linux-kernel - Re: [PATCH 1/1 linux-next] fs/coda/upcall.c: remove UPARG flow control macro

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Date:	Mon, 27 Apr 2015 21:44:17 +0200 (CEST)
From:	Fabian Frederick <fabf@...net.be>
To:	Jan Harkes <jaharkes@...cmu.edu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, coda@...cmu.edu
Subject: Re: [PATCH 1/1 linux-next] fs/coda/upcall.c: remove UPARG flow
 control macro



> On 27 April 2015 at 20:37 Jan Harkes <jaharkes@...cmu.edu> wrote:
>
>
> On Mon, Apr 27, 2015 at 07:23:06PM +0200, Fabian Frederick wrote:
> > Move UPARG code to alloc_upcall() and test errors/return in callsites.
> > This patch removes flow control in macros which must be avoided.
> > (See Documentation/CodingStyle)
>
> At first glance this is not a correct patch.
>
> UPARG allocates a buffer that is large enough to hold both the upcall
> message going to userspace as well as the incoming reply message. At
> first glance this patch only seems to allocate insize. It may still be
> doing the right thing because insize is defined at the call level as
> MAX(sizeof(inarg), sizeof(outarg)). This it looks like quite a few
> changes for an untested patch and not enough for an actual cleanup of
> the related code.
>
> Jan

Sorry Jan but I don't see any problem in that patch.
outarg is processed the same way:

New alloc_upcall(**inp, **outp):
*outp = (union outputArgs *)inp;
*outsize = insize;

UPARG macro:
outp = (union outputArgs *)(inp); \
outsize = insize; \

Regards,
Fabian


>
> > ---
> > This is untested.
> >
> >  fs/coda/upcall.c | 107
> >+++++++++++++++++++++++++++++++++++--------------------
> >  1 file changed, 69 insertions(+), 38 deletions(-)
> >
> > diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c
> > index 9b1ffaa..7524f630 100644
> > --- a/fs/coda/upcall.c
> > +++ b/fs/coda/upcall.c
> > @@ -41,30 +41,24 @@
> >  static int coda_upcall(struct venus_comm *vc, int inSize, int *outSize,
> >                    union inputArgs *buffer);
> > 
> > -static void *alloc_upcall(int opcode, int size)
> > +static int alloc_upcall(int opcode, int insize, int *outsize,
> > +                   union inputArgs **inp, union outputArgs **outp)
> >  {
> > -   union inputArgs *inp;
> > +   CODA_ALLOC(*inp, union inputArgs *, insize);
> > +   if (!*inp)
> > +           return -ENOMEM;
> > 
> > -   CODA_ALLOC(inp, union inputArgs *, size);
> > -        if (!inp)
> > -           return ERR_PTR(-ENOMEM);
> ...
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