linux-kernel - Re: [2/2] spi: Add SPI master controller for OCTEON SOCs.

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Date:	Tue, 21 Aug 2012 12:49:36 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	David Daney <ddaney.cavm@...il.com>
Cc:	devicetree-discuss@...ts.ozlabs.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org,
	linux-doc@...r.kernel.org, David Daney <david.daney@...ium.com>
Subject: Re: [2/2] spi: Add SPI master controller for OCTEON SOCs.

On Fri, May 11, 2012 at 08:34:46PM -0000, David Daney wrote:
> From: David Daney <david.daney@...ium.com>
> 
> Add the driver, link it into the kbuild system and provide device tree
> binding documentation.
> 
> Signed-off-by: David Daney <david.daney@...ium.com>
> Acked-by: Grant Likely <grant.likely@...retlab.ca>
> 
[ ... ]

> +
> +static int __devexit octeon_spi_remove(struct platform_device *pdev)
> +{
> +	struct octeon_spi *p = platform_get_drvdata(pdev);
> +	struct spi_master *master = p->my_master;
> +
> +	spi_unregister_master(master);
> +

I know it is a bit late, but ...

The call to spi_unregister_master() frees the memory associated with master,
ie 'p', and the spi_master_put() below without matching spi_master_get() is
unnecessary/wrong. One possible fix would be to use 

	struct spi_master *master = spi_master_get(p->my_master);

above. That protects master and p while it is still being used, and makes use
of the call to spi_master_put() below. Another option might be to move
cvmx_write_csr() ahead of the call to spi_unregister_master() and drop the
call to spi_master_put().

Guenter

> +	/* Clear the CSENA* and put everything in a known state. */
> +	cvmx_write_csr(p->register_base + OCTEON_SPI_CFG, 0);
> +	spi_master_put(master);
> +	return 0;
> +}
> +
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