linux-kernel - Re: [Stable-review] [24/28] USB: xhci

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Date:	Wed, 20 Apr 2011 03:02:04 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Dmitry Torokhov <dtor@...are.com>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	stable-review@...nel.org, alan@...rguk.ukuu.org.uk,
	Greg KH <gregkh@...e.de>
Subject: Re: [Stable-review] [24/28] USB: xhci - fix unsafe macro
 definitions

On Tue, 2011-04-19 at 13:31 -0700, Greg KH wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> 
> From: Dmitry Torokhov <dtor@...are.com>
> 
> commit 5a6c2f3ff039154872ce597952f8b8900ea0d732 upstream.
> 
> Macro arguments used in expressions need to be enclosed in parenthesis
> to avoid unpleasant surprises.

Do you know of any specific uses of these macros where the missing
parentheses caused 'unpleasant surprises'?

Ben.

> This should be queued for kernels back to 2.6.31
> 
> Signed-off-by: Dmitry Torokhov <dtor@...are.com>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  drivers/usb/host/xhci.h |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -232,7 +232,7 @@ struct xhci_op_regs {
>   * notification type that matches a bit set in this bit field.
>   */
>  #define	DEV_NOTE_MASK		(0xffff)
> -#define ENABLE_DEV_NOTE(x)	(1 << x)
> +#define ENABLE_DEV_NOTE(x)	(1 << (x))
>  /* Most of the device notification types should only be used for debug.
>   * SW does need to pay attention to function wake notifications.
>   */
> @@ -579,11 +579,11 @@ struct xhci_ep_ctx {
>  #define EP_STATE_STOPPED	3
>  #define EP_STATE_ERROR		4
>  /* Mult - Max number of burtst within an interval, in EP companion desc. */
> -#define EP_MULT(p)		((p & 0x3) << 8)
> +#define EP_MULT(p)		(((p) & 0x3) << 8)
>  /* bits 10:14 are Max Primary Streams */
>  /* bit 15 is Linear Stream Array */
>  /* Interval - period between requests to an endpoint - 125u increments. */
> -#define EP_INTERVAL(p)		((p & 0xff) << 16)
> +#define EP_INTERVAL(p)		(((p) & 0xff) << 16)
>  #define EP_INTERVAL_TO_UFRAMES(p)		(1 << (((p) >> 16) & 0xff))
>  
>  /* ep_info2 bitmasks */
> 
> 
> _______________________________________________
> Stable-review mailing list
> Stable-review@...ux.kernel.org
> http://linux.kernel.org/mailman/listinfo/stable-review
> 

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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