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Date: Thu, 3 Sep 2015 22:55:44 +0200 (CEST)
From: Julia Lawall <julia.lawall@lip6.fr>
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To: Linus Torvalds <torvalds@linux-foundation.org>
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On Thu, 3 Sep 2015, Linus Torvalds wrote:

> On Thu, Sep 3, 2015 at 12:32 PM, Julia Lawall <julia.lawall@lip6.fr> wrote:
> >
> > I find 518 occurrences of a function parameter declaration that contains
> > an explicit size.  But only the sizeof(mcs_mask) where there is a sizeof
> > on such a parameter.  I also checked for ARRAY_SIZE on such parameters,
> > and didn't find any occurrences of that either.
> 
> Are there any cases of multi-dimensional arrays? Because those
> actually have semantic meaning outside of sizeof(), just in things
> like adding offsets.
> 
> Eg something like
> 
>      int fn(int a[][10])
> 
> ends up being equivalent to something like
> 
>      int fn(int (*a)[10])
> 
> and "a+1" is actually 40 bytes ahead of "a", so it does *not* act like
> an "int *".
> 
> (And I might have screwed that up mightily - C multidimensional arrays
> and the conversions to pointers are really easy to get confused about.
> Which is why I hope we don't have them)

There are 32 2-dimensional arrays in function parameters, and 1 
3-dimensional array.  No 4-dimensional arrays.  I didn't check past that.  
None of these has a sizeof or ARRAY_SIZE.

The three dimensional array is here: drivers/media/dvb-frontends/stv0367.c

static int stv0367ter_filt_coeff_init(struct stv0367_state *state,
                                u16 CellsCoeffs[3][6][5], u32 DemodXtal)

It is used as follows:

                       stv0367_writereg(state,
                                (R367TER_IIRCX_COEFF1_MSB + 2 * (j - 1)),
                                MSB(CellsCoeffs[k][i-1][j-1]));
                        stv0367_writereg(state,
                                (R367TER_IIRCX_COEFF1_LSB + 2 * (j - 1)),
                                LSB(CellsCoeffs[k][i-1][j-1]));

The value of this parameter is one of three locally defined static global 
arrays.

julia