perf/x86/intel, watchdog/core: Sanitize PMU HT bug workaround

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 <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Don Zickus <dzickus@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Link: http://lkml.kernel.org/r/20170912194146.247141871@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 829e89c..9fb9a1f 100644 (file)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4409,10 +4409,9 @@ 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);
 
@@ -4420,9 +4419,7 @@ 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);