add upper-32-bits macro (218e180e) · Commits · 戴 / test

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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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 */

Admin message