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Commit 67f03de5 authored by David Hildenbrand's avatar David Hildenbrand Committed by Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 0c00b1e0

arch/s390/kernel/time.c

+0 −5
Original line number Diff line number Diff line
@@ -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;

}



/*