__module_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.
Replace the preempt_disable() section around __module_address() with
RCU.
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Eduard Zingerman <eddyz87@xxxxxxxxx>
Cc: Hao Luo <haoluo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Matt Bobrowski <mattbobrowski@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Yonghong Song <yonghong.song@xxxxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Cc: linux-trace-kernel@xxxxxxxxxxxxxxx
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
The previous version was broken in terms that the break statement broke
out of the scoped_guard loop and added something to the list. This is
now fixed by adding the "skip_add" bool.
While at it, I updated the comment by removing the "we".
kernel/trace/bpf_trace.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index adc947587eb81..e6a17a60d8787 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2345,10 +2345,9 @@ void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
{
struct module *mod;
- preempt_disable();
+ guard(rcu)();
mod = __module_address((unsigned long)btp);
module_put(mod);
- preempt_enable();
}
static __always_inline
@@ -2932,18 +2931,21 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3
u32 i, err = 0;
for (i = 0; i < addrs_cnt; i++) {
+ bool skip_add = false;
struct module *mod;
- preempt_disable();
- mod = __module_address(addrs[i]);
- /* Either no module or we it's already stored */
- if (!mod || has_module(&arr, mod)) {
- preempt_enable();
- continue;
+ scoped_guard(rcu) {
+ mod = __module_address(addrs[i]);
+ /* Either no module or it's already stored */
+ if (!mod || has_module(&arr, mod)) {
+ skip_add = true;
+ break; /* scoped_guard */
+ }
+ if (!try_module_get(mod))
+ err = -EINVAL;
}
- if (!try_module_get(mod))
- err = -EINVAL;
- preempt_enable();
+ if (skip_add)
+ continue;
if (err)
break;
err = add_module(&arr, mod);
--
2.47.2
