diff options
| author | Sven Schnelle <svens@linux.ibm.com> | 2025-07-03 13:50:27 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-20 18:30:32 +0200 |
| commit | c999814d0b9f4435a48077801fc8e9c10fdd3617 (patch) | |
| tree | 91fe5aac67f0fd9667a8c4477c966bc131a9cc14 | |
| parent | 56cabce6229ad9a32065f82e2821054cb05af3c3 (diff) | |
s390/stp: Remove udelay from stp_sync_clock()
[ Upstream commit b367017cdac21781a74eff4e208d3d38e1f38d3f ]
When an stp sync check is handled on a system with multiple
cpus each cpu gets a machine check but only the first one
actually handles the sync operation. All other CPUs spin
waiting for the first one to finish with a short udelay().
But udelay can't be used here as the first CPU modifies tod_clock_base
before performing the sync op. During this timeframe
get_tod_clock_monotonic() might return a non-monotonic time.
The time spent waiting should be very short and udelay is a busy loop
anyways, therefore simply remove the udelay.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/s390/kernel/time.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index b713effe0579..96fc41f26d7e 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -579,7 +579,7 @@ static int stp_sync_clock(void *data) atomic_dec(&sync->cpus); /* Wait for in_sync to be set. */ while (READ_ONCE(sync->in_sync) == 0) - __udelay(1); + ; } if (sync->in_sync != 1) /* Didn't work. Clear per-cpu in sync bit again. */ |