Re: 3.14.23-rt20 - x86, UV: raw_spinlock conversion
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2015-02-17 13:02:54
Also in:
lkml
* Mike Galbraith | 2014-11-02 08:31:37 [+0100]:
Shrug. Lots of hobbyists have a beast in their basement, right?
I can take this as is if you want.
quoted hunk ↗ jump to hunk
--- a/arch/x86/platform/uv/uv_time.c +++ b/arch/x86/platform/uv/uv_time.c@@ -300,13 +300,18 @@ static int uv_rtc_unset_timer(int cpu, istatic cycle_t uv_read_rtc(struct clocksource *cs) { unsigned long offset; + cycle_t cycles; + migrate_disable(); if (uv_get_min_hub_revision_id() == 1) offset = 0; else offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE; - return (cycle_t)uv_read_local_mmr(UVH_RTC | offset); + cycles = (cycle_t)uv_read_local_mmr(UVH_RTC | offset); + migrate_enable(); + + return cycles; }
but do you really want a migrate_disable() in here? The only problem I can imagine is that you switch CPUs between uv_blade_processor_id() and the actual read. I recommend preempt_disable() and sending this upstream as well since it is not limited to -RT. Sebastian