Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763852AbXHaDlq (ORCPT ); Thu, 30 Aug 2007 23:41:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757083AbXHaDlh (ORCPT ); Thu, 30 Aug 2007 23:41:37 -0400 Received: from pythia.bakeyournoodle.com ([203.82.209.197]:52378 "EHLO pythia.bakeyournoodle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751007AbXHaDlg (ORCPT ); Thu, 30 Aug 2007 23:41:36 -0400 X-Greylist: delayed 366 seconds by postgrey-1.27 at vger.kernel.org; Thu, 30 Aug 2007 23:41:35 EDT Date: Fri, 31 Aug 2007 13:41:34 +1000 To: Linux Kernel ML , Andrew Morton Cc: Andi Kleen , Tony Luck , John Stultz Subject: [PATCH] Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday(). Message-ID: <20070831034134.GP10345@bakeyournoodle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: Mutt/1.5.13 (2006-08-11) From: tony@bakeyournoodle.com (Tony Breeds) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4015 Lines: 121 On platforms that copy sys_tz into the vdso (currently only x86_64, soon to include powerpc), it is possible for the vdso to get out of sync if a user calls (admittedly unusual) settimeofday(NULL, ptr). This patch adds a hook for architectures that set CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also updater their copy in the vdso. Signed-off-by: Tony Breeds Cc: Andi Kleen Cc: Tony Luck Cc: John Stultz --- Only compile tested for IA64 Testcase at: http://bakeyournoodle.com/~tony/settimeofday-0.0/ I guess this is aimed at 2.6.24 arch/ia64/kernel/time.c | 5 +++++ arch/x86_64/kernel/vsyscall.c | 11 ++++++++++- include/linux/clocksource.h | 5 +++++ kernel/time.c | 2 ++ 4 files changed, 22 insertions(+), 1 deletions(-) diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index 98cfc90..2bb8421 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c @@ -371,6 +371,11 @@ ia64_setup_printk_clock(void) ia64_printk_clock = ia64_itc_printk_clock; } +/* IA64 doesn't cache the timezone */ +void update_vsyscall_tz(void) +{ +} + void update_vsyscall(struct timespec *wall, struct clocksource *c) { unsigned long flags; diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c index 06c3494..4ff78b0 100644 --- a/arch/x86_64/kernel/vsyscall.c +++ b/arch/x86_64/kernel/vsyscall.c @@ -66,6 +66,16 @@ struct vsyscall_gtod_data __vsyscall_gtod_data __section_vsyscall_gtod_data = .sysctl_enabled = 1, }; +void update_vsyscall_tz(void) +{ + unsigned long flags; + + write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags); + /* sys_tz has changed */ + vsyscall_gtod_data.sys_tz = sys_tz; + write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags); +} + void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) { unsigned long flags; @@ -79,7 +89,6 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) vsyscall_gtod_data.clock.shift = clock->shift; vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec; vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec; - vsyscall_gtod_data.sys_tz = sys_tz; vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec; vsyscall_gtod_data.wall_to_monotonic = wall_to_monotonic; write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags); diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 16ea337..107787a 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -221,10 +221,15 @@ extern void clocksource_resume(void); #ifdef CONFIG_GENERIC_TIME_VSYSCALL extern void update_vsyscall(struct timespec *ts, struct clocksource *c); +extern void update_vsyscall_tz(void); #else static inline void update_vsyscall(struct timespec *ts, struct clocksource *c) { } + +static inline void update_vsyscall_tz(void) +{ +} #endif #endif /* _LINUX_CLOCKSOURCE_H */ diff --git a/kernel/time.c b/kernel/time.c index 2289a8d..9a4873e 100644 --- a/kernel/time.c +++ b/kernel/time.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include #include @@ -163,6 +164,7 @@ int do_sys_settimeofday(struct timespec *tv, struct timezone *tz) if (tz) { /* SMP safe, global irq locking makes it work. */ sys_tz = *tz; + update_vsyscall_tz(); if (firsttime) { firsttime = 0; if (!tv) -- 1.5.2.5 Yours Tony linux.conf.au http://linux.conf.au/ || http://lca2008.linux.org.au/ Jan 28 - Feb 02 2008 The Australian Linux Technical Conference! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/