Commit-ID: 1ba143a5216fb148211160a0ecc1f8d3f92f06bb
Gitweb: http://git.kernel.org/tip/1ba143a5216fb148211160a0ecc1f8d3f92f06bb
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Wed, 24 May 2017 10:15:30 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 26 May 2017 10:10:43 +0200
perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode()
If intel_snb_check_microcode() is invoked via
microcode_init -> perf_check_microcode -> intel_snb_check_microcode
then get_online_cpus() is invoked nested. This works with the current
implementation of get_online_cpus() but prevents converting it to a percpu
rwsem.
intel_snb_check_microcode() is also invoked from intel_sandybridge_quirk()
unprotected.
Drop get_online_cpus() from intel_snb_check_microcode() and add it to
intel_sandybridge_quirk() so both call sites are protected.
Convert *_online_cpus() to the new interfaces while at it.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20170524081548.594862191@xxxxxxxxxxxxx
---
arch/x86/events/intel/core.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index a6d91d4..b9174aa 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3410,12 +3410,10 @@ static void intel_snb_check_microcode(void)
int pebs_broken = 0;
int cpu;
- get_online_cpus();
for_each_online_cpu(cpu) {
if ((pebs_broken = intel_snb_pebs_broken(cpu)))
break;
}
- put_online_cpus();
if (pebs_broken == x86_pmu.pebs_broken)
return;
@@ -3488,7 +3486,9 @@ static bool check_msr(unsigned long msr, u64 mask)
static __init void intel_sandybridge_quirk(void)
{
x86_pmu.check_microcode = intel_snb_check_microcode;
+ cpus_read_lock();
intel_snb_check_microcode();
+ cpus_read_unlock();
}
static const struct { int id; char *name; } intel_arch_events_map[] __initconst = {
@@ -4112,13 +4112,12 @@ static __init int fixup_ht_bug(void)
lockup_detector_resume();
- get_online_cpus();
+ cpus_read_lock();
- for_each_online_cpu(c) {
+ for_each_online_cpu(c)
free_excl_cntrs(c);
- }
- put_online_cpus();
+ cpus_read_unlock();
pr_info("PMU erratum BJ122, BV98, HSD29 workaround disabled, HT off\n");
return 0;
}
--
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