Commit 218e180e authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

add upper-32-bits macro



We keep on getting "right shift count >= width of type" warnings when doing
things like

	sector_t s;

	x = s >> 56;

because with CONFIG_LBD=n, s is only 32-bit.  Similar problems can occur with
dma_addr_t's.

So add a simple wrapper function which code can use to avoid this warning.
The above example would become

	x = upper_32_bits(s) >> 24;

The first user is in fact AFS.

Cc: James Bottomley <James.Bottomley@SteelEye.com>
Cc: "Cameron, Steve" <Steve.Cameron@hp.com>
Cc: "Miller, Mike (OS Dev)" <Mike.Miller@hp.com>
Cc: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 894b8788
...@@ -41,6 +41,16 @@ extern const char linux_proc_banner[]; ...@@ -41,6 +41,16 @@ extern const char linux_proc_banner[];
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y)) #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
/**
* upper_32_bits - return bits 32-63 of a number
* @n: the number we're accessing
*
* A basic shift-right of a 64- or 32-bit quantity. Use this to suppress
* the "right shift count >= width of type" warning when that quantity is
* 32-bits.
*/
#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
#define KERN_EMERG "<0>" /* system is unusable */ #define KERN_EMERG "<0>" /* system is unusable */
#define KERN_ALERT "<1>" /* action must be taken immediately */ #define KERN_ALERT "<1>" /* action must be taken immediately */
#define KERN_CRIT "<2>" /* critical conditions */ #define KERN_CRIT "<2>" /* critical conditions */
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment