From: Qian Cai <cai@lca.pw>
To: akpm@linux-foundation.org
Cc: davem@davemloft.net, arnd@arndb.de, dhowells@redhat.com,
ndesaulniers@google.com, morbo@google.com, jyknight@google.com,
natechancellor@gmail.com, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, Qian Cai <cai@lca.pw>
Subject: [PATCH v2] asm-generic: fix -Wtype-limits compiler warnings
Date: Wed, 24 Jul 2019 16:29:26 -0400 [thread overview]
Message-ID: <1564000166-31428-1-git-send-email-cai@lca.pw> (raw)
The 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.
Fixes: d66acc39c7ce ("bitops: Optimise get_order()")
Signed-off-by: Qian Cai <cai@lca.pw>
---
v2: Kill off __get_order() per Andrew.
Update the comments per David.
Remove a variable "order" to be consistent with the rest of return
statements.
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 c64bea7a52be..e9f20b813a69 100644
--- a/include/asm-generic/getorder.h
+++ b/include/asm-generic/getorder.h
@@ -7,24 +7,6 @@
#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
@@ -43,19 +25,27 @@ 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__ */
--
1.8.3.1
reply other threads:[~2019-07-24 20:29 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1564000166-31428-1-git-send-email-cai@lca.pw \
--to=cai@lca.pw \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=davem@davemloft.net \
--cc=dhowells@redhat.com \
--cc=jyknight@google.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=morbo@google.com \
--cc=natechancellor@gmail.com \
--cc=ndesaulniers@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).