Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1687189

[PATCH 07/14] proc/kcore: hide a harmless warning

From Arnd Bergmann <arnd@arndb.de>
Newsgroups linux.kernel
Subject [PATCH 07/14] proc/kcore: hide a harmless warning
Date 2017-07-14 11:30 +0200
Message-ID <u3559-1oP-37@gated-at.bofh.it> (permalink)
References <u3558-1oP-15@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

gcc warns when MODULES_VADDR/END is defined to the same value as
VMALLOC_START/VMALLOC_END, e.g. on x86-32:

fs/proc/kcore.c: In function ‘add_modules_range’:
fs/proc/kcore.c:622:161: error: self-comparison always evaluates to false [-Werror=tautological-compare]
  if (/*MODULES_VADDR != VMALLOC_START && */MODULES_END != VMALLOC_END) {

The code is correct as it is required for most other configurations.
The best workaround I found for shutting up that warning is to make
it a little more complex by adding a temporary variable. The compiler
will still optimize away the code as it finds the two to be identical,
but it no longer warns because it doesn't condider the comparison
"tautological" any more.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 fs/proc/kcore.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 45629f4b5402..c503ad657c46 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -620,12 +620,14 @@ static void __init proc_kcore_text_init(void)
 /*
  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
  */
-struct kcore_list kcore_modules;
+static struct kcore_list kcore_modules;
 static void __init add_modules_range(void)
 {
-	if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
-		kclist_add(&kcore_modules, (void *)MODULES_VADDR,
-			MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
+	void *start = (void *)MODULES_VADDR;
+	size_t len = MODULES_END - MODULES_VADDR;
+
+	if (start != (void *)VMALLOC_START && len != VMALLOC_END - VMALLOC_START) {
+		kclist_add(&kcore_modules, start, len, KCORE_VMALLOC);
 	}
 }
 #else
-- 
2.9.0

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 00/14] gcc-7 warnings Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:30 +0200
  [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:30 +0200
    Re: [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning Joe Perches <joe@perches.com> - 2017-07-14 12:10 +0200
      Re: [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 12:40 +0200
        Re: [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning Kevin Easton <kevin@guarana.org> - 2017-07-15 06:30 +0200
  [PATCH 04/14] x86: math-emu: avoid -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:30 +0200
  [PATCH 07/14] proc/kcore: hide a harmless warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:30 +0200
    Re: [PATCH 07/14] proc/kcore: hide a harmless warning Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-07-14 14:30 +0200
  [PATCH 13/14] iopoll: avoid -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
    Re: [PATCH 13/14] iopoll: avoid -Wint-in-bool-context warning Joe Perches <joe@perches.com> - 2017-07-14 12:00 +0200
      Re: [PATCH 13/14] iopoll: avoid -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 12:30 +0200
  [PATCH 09/14] SFI: fix tautological-compare warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
  [PATCH 11/14] IB/uverbs: fix gcc-7 type warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
    Re: [PATCH 11/14] IB/uverbs: fix gcc-7 type warning Leon Romanovsky <leon@kernel.org> - 2017-07-14 11:50 +0200
  [PATCH 10/14] staging:iio:resolver:ad2s1210 fix negative IIO_ANGL_VEL read Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
    Re: [PATCH 10/14] staging:iio:resolver:ad2s1210 fix negative  IIO_ANGL_VEL read Jonathan Cameron <jic23@kernel.org> - 2017-07-15 13:50 +0200
  [PATCH 12/14] drm/nouveau/clk: fix gcc-7 -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
  [PATCH 06/14] acpi: thermal: fix gcc-6/ccache warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
  [PATCH 08/14] Input: adxl34x - fix gcc-7 -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:40 +0200
    Re: [PATCH 08/14] Input: adxl34x - fix gcc-7 -Wint-in-bool-context warning Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-14 21:30 +0200
      Re: [PATCH 08/14] Input: adxl34x - fix gcc-7 -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 22:20 +0200
        Re: [PATCH 08/14] Input: adxl34x - fix gcc-7 -Wint-in-bool-context  warning Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-07-14 23:50 +0200
  [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result interpreted as bool Arnd Bergmann <arnd@arndb.de> - 2017-07-14 11:50 +0200
    Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Dan Carpenter <dan.carpenter@oracle.com> - 2017-07-14 14:10 +0200
      Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:30 +0200
        Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Dan Carpenter <dan.carpenter@oracle.com> - 2017-07-14 15:00 +0200
          Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Dan Carpenter <dan.carpenter@oracle.com> - 2017-07-14 15:20 +0200
            Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Arnd Bergmann <arnd@arndb.de> - 2017-07-14 21:40 +0200
    Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Dan Carpenter <dan.carpenter@oracle.com> - 2017-07-14 14:50 +0200
    Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Hans Verkuil <hverkuil@xs4all.nl> - 2017-07-17 15:50 +0200
      Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Arnd Bergmann <arnd@arndb.de> - 2017-07-17 16:30 +0200
        Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Hans Verkuil <hverkuil@xs4all.nl> - 2017-07-17 16:40 +0200
          Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Arnd Bergmann <arnd@arndb.de> - 2017-07-17 23:30 +0200
        Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Dan Carpenter <dan.carpenter@oracle.com> - 2017-07-17 16:40 +0200
        Re: [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result  interpreted as bool Hans Verkuil <hverkuil@xs4all.nl> - 2017-07-17 16:40 +0200
  Re: [PATCH 00/14] gcc-7 warnings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-14 12:30 +0200

csiph-web