Commit bdba0051 authored Jan 07, 2013 by Will Deacon Committed by Catalin Marinas Jan 10, 2013

arm64: vdso: remove broken, redundant sequence counting for timezones



This patch is an arm64 version of ce73ec6d ("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 <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent 9931faca

arch/arm64/kernel/vdso.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -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;
		}

arch/arm64/kernel/vdso/gettimeofday.S

+0 −2

Original line number	Diff line number	Diff line
		@@ -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

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