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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -41,6 +41,16 @@ extern const char linux_proc_banner[];
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#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
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#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
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/**
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* upper_32_bits - return bits 32-63 of a number
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* @n: the number we're accessing
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*
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* A basic shift-right of a 64- or 32-bit quantity. Use this to suppress
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* the "right shift count >= width of type" warning when that quantity is
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* 32-bits.
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*/
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#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
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#define KERN_EMERG "<0>" /* system is unusable */
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#define KERN_ALERT "<1>" /* action must be taken immediately */
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#define KERN_CRIT "<2>" /* critical conditions */
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