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| author |   David Hildenbrand <dahi@linux.vnet.ibm.com> | 2016-07-18 17:10:17 +0200 |
|---|---|---|
| committer |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-08-29 11:04:58 +0200 |
| commit | 67f03de5f0ad6b4b0481bb43e4a819d1a441900b (patch) | |
| tree | 085d38da1501517aea60964199638d4fa264983e | |
| parent | s390/time: fixup the clock comparator on all cpus (diff) | |
| download | linux-dev-67f03de5f0ad6b4b0481bb43e4a819d1a441900b.tar.xz linux-dev-67f03de5f0ad6b4b0481bb43e4a819d1a441900b.zip | |
s390/time: avoid races when updating tb_update_count
The increment might not be atomic and we're not holding the
timekeeper_lock. Therefore we might lose an update to count, resulting in
VDSO being trapped in a loop. As other archs also simply update the
values and count doesn't seem to have an impact on reloading of these
values in VDSO code, let's just remove the update of tb_update_count.
Suggested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/kernel/time.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 5b1a199667e2..0bfcc492987e 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -278,13 +278,8 @@ extern struct timezone sys_tz; void update_vsyscall_tz(void) { - /* Make userspace gettimeofday spin until we're done. */ - ++vdso_data->tb_update_count; - smp_wmb(); vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; vdso_data->tz_dsttime = sys_tz.tz_dsttime; - smp_wmb(); - ++vdso_data->tb_update_count; } /* |