[patch 2.6.22-rc3-git] SPI dynamic busid generation bugfix

[patch 2.6.22-rc3-git] SPI dynamic busid generation bugfix

[David Brownell]

Fix SPI dynamic bus ID assignment to start at 2^15-1 rather than
a negative number.  Valid bus ids are supposed to be positive,
and are (now) stored in an 's16' value.

Signed-off-by: David Brownell <dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>

--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -411,7 +411,7 @@ EXPORT_SYMBOL_GPL(spi_alloc_master);
  */
 int spi_register_master(struct spi_master *master)
 {
-	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
+	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
 	struct device		*dev = master->cdev.dev;
 	int			status = -ENODEV;
 	int			dynamic = 0;

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Re: [patch 2.6.22-rc3-git] SPI dynamic busid generation bugfix

[Andrew Morton]

On Fri, 1 Jun 2007 16:12:19 -0700
David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org> wrote:

> Fix SPI dynamic bus ID assignment to start at 2^15-1 rather than
> a negative number.  Valid bus ids are supposed to be positive,
> and are (now) stored in an 's16' value.
> 
> Signed-off-by: David Brownell <dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
> 
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -411,7 +411,7 @@ EXPORT_SYMBOL_GPL(spi_alloc_master);
>   */
>  int spi_register_master(struct spi_master *master)
>  {
> -	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
> +	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
>  	struct device		*dev = master->cdev.dev;
>  	int			status = -ENODEV;
>  	int			dynamic = 0;

Is this going to underflow then malfunction after 32k modprobe+rmmods?

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Re: [patch 2.6.22-rc3-git] SPI dynamic busid generation bugfix

[David Brownell]

On Friday 01 June 2007, Andrew Morton wrote:
> 
> Is this going to underflow then malfunction after 32k modprobe+rmmods?

Yes.  A better fix will be needed, for the crazy people amongst us.
Dynamic busids are quite uncommon though, so that's not pressing.

- Dave




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Re: [patch 2.6.22-rc3-git] SPI dynamic busid generation bugfix

[Andrew Morton]

On Fri, 1 Jun 2007 16:46:12 -0700
David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org> wrote:

> On Friday 01 June 2007, Andrew Morton wrote:
> > 
> > Is this going to underflow then malfunction after 32k modprobe+rmmods?
> 
> Yes.  A better fix will be needed, for the crazy people amongst us.
> Dynamic busids are quite uncommon though, so that's not pressing.

lib/idr.c can be used for this.  There are patches in Greg's driver
tree which make it better-suited.

The give-me-a-unique-integer thing is so common that we really should
have a wrapper around idr which does just that.

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