[GIT pull] perf/urgent for 5.3-rc5

From: Thomas Gleixner
Date: Sun Aug 25 2019 - 05:45:50 EST


Linus,

please pull the latest perf-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus

up to: f1c6ece23729: kprobes: Fix potential deadlock in kprobe_optimizer()

Two small fixes for kprobes and perf:

- Prevent a deadlock in kprobe_optimizer() causes by reverse lock
ordering

- Fix a comment typo

Thanks,

tglx

------------------>
Andrea Righi (1):
kprobes: Fix potential deadlock in kprobe_optimizer()

Su Yanjun (1):
perf/x86: Fix typo in comment


arch/x86/events/core.c | 2 +-
kernel/kprobes.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 81b005e4c7d9..325959d19d9a 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1236,7 +1236,7 @@ void x86_pmu_enable_event(struct perf_event *event)
* Add a single event to the PMU.
*
* The event is added to the group of enabled events
- * but only if it can be scehduled with existing events.
+ * but only if it can be scheduled with existing events.
*/
static int x86_pmu_add(struct perf_event *event, int flags)
{
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9873fc627d61..d9770a5393c8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -470,6 +470,7 @@ static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
*/
static void do_optimize_kprobes(void)
{
+ lockdep_assert_held(&text_mutex);
/*
* The optimization/unoptimization refers online_cpus via
* stop_machine() and cpu-hotplug modifies online_cpus.
@@ -487,9 +488,7 @@ static void do_optimize_kprobes(void)
list_empty(&optimizing_list))
return;

- mutex_lock(&text_mutex);
arch_optimize_kprobes(&optimizing_list);
- mutex_unlock(&text_mutex);
}

/*
@@ -500,6 +499,7 @@ static void do_unoptimize_kprobes(void)
{
struct optimized_kprobe *op, *tmp;

+ lockdep_assert_held(&text_mutex);
/* See comment in do_optimize_kprobes() */
lockdep_assert_cpus_held();

@@ -507,7 +507,6 @@ static void do_unoptimize_kprobes(void)
if (list_empty(&unoptimizing_list))
return;

- mutex_lock(&text_mutex);
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop free_list for disarming */
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
@@ -524,7 +523,6 @@ static void do_unoptimize_kprobes(void)
} else
list_del_init(&op->list);
}
- mutex_unlock(&text_mutex);
}

/* Reclaim all kprobes on the free_list */
@@ -556,6 +554,7 @@ static void kprobe_optimizer(struct work_struct *work)
{
mutex_lock(&kprobe_mutex);
cpus_read_lock();
+ mutex_lock(&text_mutex);
/* Lock modules while optimizing kprobes */
mutex_lock(&module_mutex);

@@ -583,6 +582,7 @@ static void kprobe_optimizer(struct work_struct *work)
do_free_cleaned_kprobes();

mutex_unlock(&module_mutex);
+ mutex_unlock(&text_mutex);
cpus_read_unlock();
mutex_unlock(&kprobe_mutex);