Re: [PATCH] new kqueue API v.08

From: Andi Kleen
Date: Sat Dec 19 2009 - 06:36:22 EST



I like the basic idea of a type safe FIFO.

> #define DYNAMIC
> #ifdef DYNAMIC
> static DECLARE_KFIFO_PTR(test[1], int);
> #else
> static DECLARE_KFIFO(test[1], int, FIFO_SIZE);

The [1] looks weird. Is that really needed and what does it mean?
The callers below don't seem to use it like an array.

> I know that this kind of macros are very sophisticated and not easy to
> maintain. But i have all tested and it works as expected. I analyzed the
> output of the compiler and for the x86 the code is as good as hand
> written assembler code.

Linux has a long tradition of complicated macros in headers, that shouldn't be a
problem.

> include/linux/kfifo.h | 1107 +++++++++++++++++++++++++++++---------------------
> kernel/kfifo.c | 768 +++++++++++++++++++++++-----------
> 2 files changed, 1174 insertions(+), 701 deletions(-)
>
> diff -u -N -r -p mmotm.orig/include/linux/kfifo.h mmotm.new/include/linux/kfifo.h
> --- mmotm.orig/include/linux/kfifo.h 2009-12-19 00:23:12.510334931 +0100
> +++ mmotm.new/include/linux/kfifo.h 2009-12-19 00:23:04.375307229 +0100
> @@ -1,8 +1,7 @@
> /*
> - * A generic kernel FIFO implementation.
> + * A generic kernel fifo implementation
> *
> * Copyright (C) 2009 Stefani Seibold <stefani@xxxxxxxxxxx>
> - * Copyright (C) 2004 Stelian Pop <stelian@xxxxxxxxxx>

You should probably keep the old copyright, even if not much code remains.

> +#ifdef __KERNEL__
> #include <linux/kernel.h>
> #include <linux/spinlock.h>
> +#include <linux/stddef.h>
> +#include <linux/scatterlist.h>
> +#else
> +#include "helper.h"
> +#endif

Such ifdefs should not make it into submitted code. Better use more glue
in the test program.


... didn't review the whole thing at this point ...

-Andi
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