From: Helge Deller deller@gmx.de
commit 9dc4241bb14afecd16518a0760bceb3d7359b12a upstream.
This reverts commit afdb4a5b1d340e4afffc65daa21cc71890d7d589.
It triggers RCU stalls at boot with a 32-bit kernel.
Signed-off-by: Helge Deller deller@gmx.de Noticed-by: John David Anglin dave.anglin@bell.net Cc: stable@vger.kernel.org # v5.16+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/parisc/kernel/time.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-)
--- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -249,16 +249,30 @@ void __init time_init(void) static int __init init_cr16_clocksource(void) { /* - * The cr16 interval timers are not syncronized across CPUs, even if - * they share the same socket. + * The cr16 interval timers are not syncronized across CPUs on + * different sockets, so mark them unstable and lower rating on + * multi-socket SMP systems. */ if (num_online_cpus() > 1 && !running_on_qemu) { - /* mark sched_clock unstable */ - clear_sched_clock_stable(); + int cpu; + unsigned long cpu0_loc; + cpu0_loc = per_cpu(cpu_data, 0).cpu_loc;
- clocksource_cr16.name = "cr16_unstable"; - clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE; - clocksource_cr16.rating = 0; + for_each_online_cpu(cpu) { + if (cpu == 0) + continue; + if ((cpu0_loc != 0) && + (cpu0_loc == per_cpu(cpu_data, cpu).cpu_loc)) + continue; + + /* mark sched_clock unstable */ + clear_sched_clock_stable(); + + clocksource_cr16.name = "cr16_unstable"; + clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE; + clocksource_cr16.rating = 0; + break; + } }
/* register at clocksource framework */