Commit 912420e5 authored Aug 02, 2019 by Qian Cai Committed by Greg Kroah-Hartman Aug 25, 2019

asm-generic: fix -Wtype-limits compiler warnings

[ Upstream commit cbedfe11347fe418621bd188d58a206beb676218 ]

Commit d66acc39 ("bitops: Optimise get_order()") introduced a
compilation warning because "rx_frag_size" is an "ushort" while
PAGE_SHIFT here is 16.

The commit changed the get_order() to be a multi-line macro where
compilers insist to check all statements in the macro even when
__builtin_constant_p(rx_frag_size) will return false as "rx_frag_size"
is a module parameter.

In file included from ./arch/powerpc/include/asm/page_64.h:107,
                 from ./arch/powerpc/include/asm/page.h:242,
                 from ./arch/powerpc/include/asm/mmu.h:132,
                 from ./arch/powerpc/include/asm/lppaca.h:47,
                 from ./arch/powerpc/include/asm/paca.h:17,
                 from ./arch/powerpc/include/asm/current.h:13,
                 from ./include/linux/thread_info.h:21,
                 from ./arch/powerpc/include/asm/processor.h:39,
                 from ./include/linux/prefetch.h:15,
                 from drivers/net/ethernet/emulex/benet/be_main.c:14:
drivers/net/ethernet/emulex/benet/be_main.c: In function 'be_rx_cqs_create':
./include/asm-generic/getorder.h:54:9: warning: comparison is always
true due to limited range of data type [-Wtype-limits]
   (((n) < (1UL << PAGE_SHIFT)) ? 0 :  \
         ^
drivers/net/ethernet/emulex/benet/be_main.c:3138:33: note: in expansion
of macro 'get_order'
  adapter->big_page_size = (1 << get_order(rx_frag_size)) * PAGE_SIZE;
                                 ^~~~~~~~~

Fix it by moving all of this multi-line macro into a proper function,
and killing __get_order() off.

[akpm@linux-foundation.org: remove __get_order() altogether]
[cai@lca.pw: v2]
  Link: http://lkml.kernel.org/r/1564000166-31428-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/1563914986-26502-1-git-send-email-cai@lca.pw


Fixes: d66acc39 ("bitops: Optimise get_order()")
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: James Y Knight <jyknight@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 765d9fe3

include/asm-generic/getorder.h

+20 −30

Original line number	Original line	Diff line number	Diff line
	@@ -6,24 +6,6 @@
	#include <linux/compiler.h>		#include <linux/compiler.h>
	#include <linux/log2.h>		#include <linux/log2.h>

	/*
	* Runtime evaluation of get_order()
	*/
	static inline __attribute_const__
	int __get_order(unsigned long size)
	{
	int order;

	size--;
	size >>= PAGE_SHIFT;
	#if BITS_PER_LONG == 32
	order = fls(size);
	#else
	order = fls64(size);
	#endif
	return order;
	}

	/**		/**
	* get_order - Determine the allocation order of a memory size		* get_order - Determine the allocation order of a memory size
	* @size: The size for which to get the order		* @size: The size for which to get the order
	@@ -42,19 +24,27 @@ int __get_order(unsigned long size)
	* to hold an object of the specified size.		* to hold an object of the specified size.
	*		*
	* The result is undefined if the size is 0.		* The result is undefined if the size is 0.
	*
	* This function may be used to initialise variables with compile time
	* evaluations of constants.
	*/		*/
	#define get_order(n) \		static inline __attribute_const__ int get_order(unsigned long size)
	( \		{
	__builtin_constant_p(n) ? ( \		if (__builtin_constant_p(size)) {
	((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT : \		if (!size)
	(((n) < (1UL << PAGE_SHIFT)) ? 0 : \		return BITS_PER_LONG - PAGE_SHIFT;
	ilog2((n) - 1) - PAGE_SHIFT + 1) \
	) : \		if (size < (1UL << PAGE_SHIFT))
	__get_order(n) \		return 0;
	)
			return ilog2((size) - 1) - PAGE_SHIFT + 1;
			}

			size--;
			size >>= PAGE_SHIFT;
			#if BITS_PER_LONG == 32
			return fls(size);
			#else
			return fls64(size);
			#endif
			}

	#endif /* __ASSEMBLY__ */		#endif /* __ASSEMBLY__ */