linux-kernel - Re: [PATCH 01/10] floppy: cleanup: expand macro FDCS

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Message-ID: <20200225180219.GA395@1wt.eu>
Date:   Tue, 25 Feb 2020 19:02:19 +0100
From:   Willy Tarreau <w@....eu>
To:     Denis Efremov <efremov@...ux.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 01/10] floppy: cleanup: expand macro FDCS

On Tue, Feb 25, 2020 at 06:22:47PM +0300, Denis Efremov wrote:
> I think that for the first attempt changing will be enough:
> -static int fdc;                        /* current fdc */
> +static int current_fdc;                        /* current fdc */
> and
> -#define FD_IOPORT fdc_state[fdc].address
> +#define FD_IOPORT fdc_state[current_fdc].address
> and for fd_setdor in ./arch/arm/include/asm/floppy.h

So after a bit more digging, that should not be correct because:
  - disk_change() uses a local "fdc" variable with expectations that
    it will be used by fd_inb(FD_DIR)
    
  - set_dor() uses a local fdc argument that's used by
    fd_outb(newdor, FD_DOR)

Here we have "fdc" hidden in:
  - FD_DOR/FD_DIR (referencing FD_IOPORT) on x86
  - fd_outb(), relying on fd_setdor() on ARM

I'm now looking how to change fd_outb() to pass the fdc in argument,
after all it's not that many places and that's exactly what we need.
Maybe afterwards we'll figure that some of them are still wrong :-)

Willy