[PATCH 4.14 237/237] s390/mm: Explicitly compare PAGE_DEFAULT_KEY against zero in storage_key_init_range

Greg Kroah-Hartman
2020-02-27T14:32:02Z

From: Nathan Chancellor <natechancellor@gmail.com>

commit 380324734956c64cd060e1db4304f3117ac15809 upstream.

Clang warns:

In file included from ../arch/s390/purgatory/purgatory.c:10:
In file included from ../include/linux/kexec.h:18:
In file included from ../include/linux/crash_core.h:6:
In file included from ../include/linux/elfcore.h:5:
In file included from ../include/linux/user.h:1:
In file included from ../arch/s390/include/asm/user.h:11:
../arch/s390/include/asm/page.h:45:6: warning: converting the result of
'<<' to a boolean always evaluates to false
[-Wtautological-constant-compare]
if (PAGE_DEFAULT_KEY)
^
../arch/s390/include/asm/page.h:23:44: note: expanded from macro
'PAGE_DEFAULT_KEY'
#define PAGE_DEFAULT_KEY (PAGE_DEFAULT_ACC << 4)
^
1 warning generated.

Explicitly compare this against zero to silence the warning as it is
intended to be used in a boolean context.

Fixes: de3fa841e429 ("s390/mm: fix compile for PAGE_DEFAULT_KEY != 0")
Link: https://github.com/ClangBuiltLinux/linux/issues/860
Link: https://lkml.kernel.org/r/20200214064207.10381-1-natechancellor@gmail.com
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/include/asm/page.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -42,7 +42,7 @@ void __storage_key_init_range(unsigned l

static inline void storage_key_init_range(unsigned long start, unsigned long end)
{
- if (PAGE_DEFAULT_KEY)
+ if (PAGE_DEFAULT_KEY != 0)
__storage_key_init_range(start, end);
}