Commit bdba0051 authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas

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: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 9931faca
......@@ -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;
}
......@@ -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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