Messages in this thread Patch in this message | | | Date | Fri, 31 Aug 2007 13:41:34 +1000 | Subject | [PATCH] Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday(). | From | (Tony Breeds) |
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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 <tony@bakeyournoodle.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Tony Luck <tony.luck@intel.com> Cc: John Stultz <johnstul@us.ibm.com> ---
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 <linux/module.h> #include <linux/timex.h> #include <linux/capability.h> +#include <linux/clocksource.h> #include <linux/errno.h> #include <linux/syscalls.h> #include <linux/security.h> @@ -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
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