From bdba0051ebcb3c6372f9cc0b2524c47cc6ce46fd Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 7 Jan 2013 16:12:31 +0000 Subject: arm64: vdso: remove broken, redundant sequence counting for timezones This patch is an arm64 version of ce73ec6db47a ("powerpc/vdso: Remove redundant locking in update_vsyscall_tz()"). Timezone data is not protected, so the sequence counter is not required to ensure consistency. Furthermore, having multiple paths updating the counter leads to a race between update_vsyscall and update_vsyscall_tz, so remove the timezone sequence counting from both the kernel and the vdso. Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/kernel/vdso.c | 4 ---- arch/arm64/kernel/vdso/gettimeofday.S | 2 -- 2 files changed, 6 deletions(-) (limited to 'arch') diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index c958cb84d75f..6a389dc1bd49 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -252,10 +252,6 @@ void update_vsyscall(struct timekeeper *tk) void update_vsyscall_tz(void) { - ++vdso_data->tb_seq_count; - smp_wmb(); vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; vdso_data->tz_dsttime = sys_tz.tz_dsttime; - smp_wmb(); - ++vdso_data->tb_seq_count; } diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S index 8bf658d974f9..f0a6d10b5211 100644 --- a/arch/arm64/kernel/vdso/gettimeofday.S +++ b/arch/arm64/kernel/vdso/gettimeofday.S @@ -73,8 +73,6 @@ ENTRY(__kernel_gettimeofday) /* If tz is NULL, return 0. */ cbz x1, 3f ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST] - seqcnt_read w9 - seqcnt_check w9, 1b stp w4, w5, [x1, #TZ_MINWEST] 3: mov x0, xzr -- cgit v1.2.3