linux-kernel - [RFT PATCH 13/13] tracing/kprobe: perf_event: Remove local kprobe event asynchronously

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Message-Id: <157918598813.29301.14393624193409447045.stgit@devnote2>
Date:   Thu, 16 Jan 2020 23:46:28 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Brendan Gregg <brendan.d.gregg@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     mhiramat@...nel.org, Ingo Molnar <mingo@...nel.org>,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        "David S . Miller" <davem@...emloft.net>, paulmck@...nel.org,
        joel@...lfernandes.org,
        "Naveen N . Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
Subject: [RFT PATCH 13/13] tracing/kprobe: perf_event: Remove local kprobe event asynchronously

Remove local kprobe event asynchronously. Note that this
can asynchronously remove a kprobe_event part, but the
perf_event needs to wait for all handlers finished before
removing the local kprobe event. So from the perf_event
(and eBPF) point of view, this shortens the trace termination
process a bit, but it still takes O(n) time to finish it.

To fix this issue, we need to change perf_event terminating
process by decoupling "disable events" and "destroy events"
as in ftrace.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/trace/trace_kprobe.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f7e0370b10ae..e8c4828c21ae 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1707,9 +1707,7 @@ void destroy_local_trace_kprobe(struct trace_event_call *event_call)
 		return;
 	}
 
-	__unregister_trace_kprobe(tk);
-
-	free_trace_kprobe(tk);
+	__unregister_trace_kprobe_async(tk);
 }
 #endif /* CONFIG_PERF_EVENTS */