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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

include/linux/kernel.h

+10 −0
Original line number Original line Diff line number Diff line
@@ -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			*/