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 18:41:10 +0200 |
| commit | 054aeb673ba3143cda4f5ccd7ba96c30a3a5f30d (patch) | |
| tree | cba9c819c22429d7fe76d47ffe96050afb723a84 | |
| parent | c82fa2c15546120517f1034e2550fe46ca7c06b4 (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 fed17d407a44..cb7ed55e24d2 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -580,7 +580,7 @@ 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. */ |