linux-kernel - Re: [PATCH] tpm: constify transmit data pointers

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Message-ID: <20170907200153.GA6350@obsidianresearch.com>
Date:   Thu, 7 Sep 2017 14:01:53 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Colin Ian King <colin.king@...onical.com>,
        tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: constify transmit data pointers

On Thu, Sep 07, 2017 at 03:30:45PM +0200, Arnd Bergmann wrote:
> Making cmd_getticks 'const' introduced a couple of harmless warnings:
> 
> drivers/char/tpm/tpm_tis_core.c: In function 'probe_itpm':
> drivers/char/tpm/tpm_tis_core.c:469:31: error: passing argument 2 of 'tpm_tis_send_data' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
>   rc = tpm_tis_send_data(chip, cmd_getticks, len);
> drivers/char/tpm/tpm_tis_core.c:477:31: error: passing argument 2 of 'tpm_tis_send_data' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
>   rc = tpm_tis_send_data(chip, cmd_getticks, len);
> drivers/char/tpm/tpm_tis_core.c:255:12: note: expected 'u8 * {aka unsigned char *}' but argument is of type 'const u8 * {aka const unsigned char *}'
>  static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
> 
> This changes the related functions to all take 'const' pointers
> so that gcc can see this as being correct. I had to slightly
> modify the logic around tpm_tis_spi_transfer() for this to work
> without introducing ugly casts.
> 
> Fixes: 5e35bd8e06b9 ("tpm_tis: make array cmd_getticks static const to shink object code size")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com>

Bit confused how the compile warnings introduced by the original patch
were missed?? Jarkko do you run compile tests and sparse before
sending pull requests?

Cheers,
Jason