[patch 02/29] perf/x86/intel: Sanitize PMU HT bug workaround

[Thomas Gleixner]

From: Peter Zijlstra <pet...@infradead.org>

The lockup_detector_suspend/resume() interface is broken in several ways
especially as it results in recursive locking of the CPU hotplug lock.

Use the new stop/restart interface in the perf NMI watchdog to temporarily
disable and reenable the already active watchdog events. That's enough to
handle it.

Signed-off-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
 arch/x86/events/intel/core.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4318,10 +4318,9 @@ static __init int fixup_ht_bug(void)
                return 0;
        }
 
-       if (lockup_detector_suspend() != 0) {
-               pr_debug("failed to disable PMU erratum BJ122, BV98, HSD29 
workaround\n");
-               return 0;
-       }
+       cpus_read_lock();
+
+       hardlockup_detector_perf_stop();
 
        x86_pmu.flags &= ~(PMU_FL_EXCL_CNTRS | PMU_FL_EXCL_ENABLED);
 
@@ -4329,9 +4328,7 @@ static __init int fixup_ht_bug(void)
        x86_pmu.commit_scheduling = NULL;
        x86_pmu.stop_scheduling = NULL;
 
-       lockup_detector_resume();
-
-       cpus_read_lock();
+       hardlockup_detector_perf_restart();
 
        for_each_online_cpu(c)
                free_excl_cntrs(c);