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From: Arnd Bergmann <arnd@arndb.de>
To: Andy Lutomirski <luto@amacapital.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>,
	Mark Rutland <mark.rutland@arm.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] x86: vdso: change time() prototype to match __vdso_time()
Date: Mon,  4 Dec 2017 16:01:55 +0100
Message-ID: <20171204150203.852959-1-arnd@arndb.de> (raw)

gcc-8 warns that time() is an alias for __vdso_time() but the two
have different prototypes:

arch/x86/entry/vdso/vclock_gettime.c:327:5: error: 'time' alias between functions of incompatible types 'int(time_t *)' {aka 'int(long int *)'} and 'time_t(time_t *)' {aka 'long int(long int *)'} [-Werror=attribute-alias]
 int time(time_t *t)
     ^~~~
arch/x86/entry/vdso/vclock_gettime.c:318:16: note: aliased declaration here

I could not figure out whether this is intentional, but I see that
changing it to return time_t avoids the warning.

Returning 'int' from time() is also a bit questionable, as it causes an
overflow in y2038 even on 64-bit architectures that use a 64-bit time_t
type. On 32-bit architecture with 64-bit time_t, time() should always
be implement by the C library by calling a (to be added) clock_gettime()
variant that takes a sufficiently wide argument.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/x86/entry/vdso/vclock_gettime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index b179d73c53bf..ebd1ab0b21a2 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -324,5 +324,5 @@ notrace time_t __vdso_time(time_t *t)
 		*t = result;
 	return result;
 }
-int time(time_t *t)
+time_t time(time_t *t)
 	__attribute__((weak, alias("__vdso_time")));
-- 
2.9.0

             reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-04 15:01 Arnd Bergmann [this message]
2017-12-06 21:21 ` [tip:x86/urgent] x86/vdso: Change " tip-bot for Arnd Bergmann

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