From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 28 Feb 2012 19:46:04 +0000 (+0000)
Subject: x86: vdso: Remove bogus locking in update_vsyscall_tz()
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=6c260d586343f7f78239d90aa9e2cfed02f74ff3;p=deliverable%2Flinux.git

x86: vdso: Remove bogus locking in update_vsyscall_tz()

Changing the sequence count in update_vsyscall_tz() is completely
pointless.

The vdso code copies the data unprotected. There is no point to change
this as sys_tz is nowhere protected at all. See sys_gettimeofday().

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index b07ba9393564..33385c18e5d3 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -80,12 +80,7 @@ early_param("vsyscall", vsyscall_setup);
 
 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 timespec *wtm,