From: Alexei Starovoitov <[email protected]>
[ Upstream commit 4580f4e0ebdf8dc8d506ae926b88510395a0c1d1 ]
Fix the following deadlock:
CPU A
_free_event()
perf_kprobe_destroy()
mutex_lock(&event_mutex)
perf_trace_event_unreg()
synchronize_rcu_tasks_trace()
There are several paths where _free_event() grabs event_mutex
and calls sync_rcu_tasks_trace. Above is one such case.
CPU B
bpf_prog_test_run_syscall()
rcu_read_lock_trace()
bpf_prog_run_pin_on_cpu()
bpf_prog_load()
bpf_tracing_func_proto()
trace_set_clr_event()
mutex_lock(&event_mutex)
Delegate trace_set_clr_event() to workqueue to avoid
such lock dependency.
Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Link:
https://lore.kernel.org/bpf/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
---
kernel/trace/bpf_trace.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index af48f66466e81..91d0d1cce09b3 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -403,7 +403,7 @@ static const struct bpf_func_proto bpf_trace_printk_proto =
{
.arg2_type = ARG_CONST_SIZE,
};
-static void __set_printk_clr_event(void)
+static void __set_printk_clr_event(struct work_struct *work)
{
/*
* This program might be calling bpf_trace_printk,
@@ -416,10 +416,11 @@ static void __set_printk_clr_event(void)
if (trace_set_clr_event("bpf_trace", "bpf_trace_printk", 1))
pr_warn_ratelimited("could not enable bpf_trace_printk events");
}
+static DECLARE_WORK(set_printk_work, __set_printk_clr_event);
const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
{
- __set_printk_clr_event();
+ schedule_work(&set_printk_work);
return &bpf_trace_printk_proto;
}
@@ -462,7 +463,7 @@ static const struct bpf_func_proto bpf_trace_vprintk_proto
= {
const struct bpf_func_proto *bpf_get_trace_vprintk_proto(void)
{
- __set_printk_clr_event();
+ schedule_work(&set_printk_work);
return &bpf_trace_vprintk_proto;
}
--
2.39.5
