[PATCH 4.4 54/78] asm-generic: fix -Wtype-limits compiler warnings

Greg Kroah-Hartman
2019-08-22T17:22:54Z

[ Upstream commit cbedfe11347fe418621bd188d58a206beb676218 ]

Commit d66acc39c7ce ("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: d66acc39c7ce ("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>
---
include/asm-generic/getorder.h | 50 ++++++++++++++--------------------
1 file changed, 20 insertions(+), 30 deletions(-)

diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h
index 65e4468ac53da..52fbf236a90ea 100644
--- a/include/asm-generic/getorder.h
+++ b/include/asm-generic/getorder.h
@@ -6,24 +6,6 @@
#include <linux/compiler.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
* @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.
*
* 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) \
-( \
- __builtin_constant_p(n) ? ( \
- ((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT : \
- (((n) < (1UL << PAGE_SHIFT)) ? 0 : \
- ilog2((n) - 1) - PAGE_SHIFT + 1) \
- ) : \
- __get_order(n) \
-)
+static inline __attribute_const__ int get_order(unsigned long size)
+{
+ if (__builtin_constant_p(size)) {
+ if (!size)
+ return BITS_PER_LONG - PAGE_SHIFT;
+
+ if (size < (1UL << PAGE_SHIFT))
+ 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__ */

--
2.20.1