From: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
To: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH/RFC] spi: Change modalias from a pointer to a character array
Date: Mon, 12 May 2008 15:18:05 -0700 [thread overview]
Message-ID: <20080512151805.4c2763b9.akpm@linux-foundation.org> (raw)
In-Reply-To: <20080509173146.2932.16141.stgit-8FIgwK2HfyId2tlXD8uQ6/kpB+XfMlBf@public.gmane.org>
On Fri, 09 May 2008 11:32:28 -0600
Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> From: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
>
> Currently, 'modalias' in the spi_device structure is a 'const char *'.
> The spi_new_device() function fills in the modalias value from a passed
> in spi_board_info data block. Since it is a pointer copy, the new
> spi_device remains dependent on the spi_board_info structure after the
> new spi_device is registered (no other fields in spi_device directly
> depend on the spi_board_info structure; all of the other data is copied).
>
> This causes a problem when dynamically propulating the list of attached
> SPI devices. For example, in arch/powerpc, the list of SPI devices can
> be populated from data in the device tree. With the current code, the
> device tree adapter must kmalloc() a new spi_board_info structure for
> each new SPI device it finds in the device tree, and there is no simple
> mechanism in place for keeping track of these allocations.
>
> This patch changes modalias from a 'const char *' to a fixed char array.
> By copying the modalias string instead of referencing it, the dependency
> on the spi_board_info structure is eliminated and an outside caller does
> not need to maintain a separate spi_board_info allocation for each device.
>
> If searched through the code to the best of my ability for any references
> to modalias which may be affected by this change and haven't found anything.
> It has been tested with the lite5200b platform in arch/powerpc.
>
> Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> ---
>
> drivers/spi/spi.c | 2 +-
> include/linux/spi/spi.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 1ad12af..bdf1b70 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -229,7 +229,7 @@ struct spi_device *spi_new_device(struct spi_master *master,
> proxy->max_speed_hz = chip->max_speed_hz;
> proxy->mode = chip->mode;
> proxy->irq = chip->irq;
> - proxy->modalias = chip->modalias;
> + strncpy(proxy->modalias, chip->modalias, KOBJ_NAME_LEN);
>
> snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
> "%s.%u", master->dev.bus_id,
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 387e428..38a080b 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -82,7 +82,7 @@ struct spi_device {
> int irq;
> void *controller_state;
> void *controller_data;
> - const char *modalias;
> + char modalias[KOBJ_NAME_LEN];
>
> /*
> * likely need more hooks for more protocol options affecting how
I'm not really able to work out if this is a needed-in-2.6.26 thing. I
assumed "not".
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next prev parent reply other threads:[~2008-05-12 22:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-09 17:32 [PATCH/RFC] spi: Change modalias from a pointer to a character array Grant Likely
[not found] ` <20080509173146.2932.16141.stgit-8FIgwK2HfyId2tlXD8uQ6/kpB+XfMlBf@public.gmane.org>
2008-05-12 22:18 ` Andrew Morton [this message]
[not found] ` <20080512151805.4c2763b9.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2008-05-12 22:20 ` Grant Likely
[not found] ` <fa686aa40805121520y979ee37ga83221b74b35afe1-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2008-05-12 22:56 ` David Brownell
2008-05-22 0:03 ` David Brownell
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