From: Masami Hiramatsu <mhiramat@kernel.org>
To: Brendan Gregg <brendan.d.gregg@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Alexei Starovoitov <ast@kernel.org>
Cc: mhiramat@kernel.org, Ingo Molnar <mingo@kernel.org>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
Daniel Borkmann <daniel@iogearbox.net>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
paulmck@kernel.org, joel@joelfernandes.org,
"Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Subject: [RFT PATCH 12/13] tracing/kprobe: Free probe event asynchronously
Date: Thu, 16 Jan 2020 23:46:17 +0900 [thread overview]
Message-ID: <157918597739.29301.3329193112465223174.stgit@devnote2> (raw)
In-Reply-To: <157918584866.29301.6941815715391411338.stgit@devnote2>
Free each probe event data structure asynchronously when
deleting probe events. But this finally synchronizes RCU
so that we make sure all event handlers have finished.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/trace/trace_dynevent.c | 5 ++++
kernel/trace/trace_kprobe.c | 46 +++++++++++++++++++++++++++++++++++------
2 files changed, 44 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 89779eb84a07..2d5e8d457309 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -70,6 +70,9 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
if (ret)
break;
}
+
+ /* Wait for running events because of async event unregistration */
+ synchronize_rcu();
mutex_unlock(&event_mutex);
return ret;
@@ -164,6 +167,8 @@ int dyn_events_release_all(struct dyn_event_operations *type)
if (ret)
break;
}
+ /* Wait for running events because of async event unregistration */
+ synchronize_rcu();
out:
mutex_unlock(&event_mutex);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 906af1ffe2b2..f7e0370b10ae 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -551,7 +551,35 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk)
}
}
-/* Unregister a trace_probe and probe_event */
+static void free_trace_kprobe_cb(struct rcu_head *head)
+{
+ struct kprobe *kp = container_of(head, struct kprobe, rcu);
+ struct kretprobe *rp = container_of(kp, struct kretprobe, kp);
+ struct trace_kprobe *tk = container_of(rp, struct trace_kprobe, rp);
+
+ if (trace_kprobe_is_return(tk))
+ kretprobe_free_callback(head);
+ else
+ kprobe_free_callback(head);
+ free_trace_kprobe(tk);
+}
+
+static void __unregister_trace_kprobe_async(struct trace_kprobe *tk)
+{
+ if (trace_kprobe_is_registered(tk)) {
+ if (trace_kprobe_is_return(tk))
+ unregister_kretprobe_async(&tk->rp,
+ free_trace_kprobe_cb);
+ else
+ unregister_kprobe_async(&tk->rp.kp,
+ free_trace_kprobe_cb);
+ }
+}
+
+/*
+ * Unregister a trace_probe and probe_event asynchronously.
+ * Caller must wait for RCU.
+ */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* If other probes are on the event, just unregister kprobe */
@@ -570,9 +598,17 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk)
return -EBUSY;
unreg:
- __unregister_trace_kprobe(tk);
dyn_event_remove(&tk->devent);
+ /*
+ * This trace_probe_unlink() can free the trace_event_call linked to
+ * this probe.
+ * We can do this before unregistering because this probe is
+ * already disabled and the disabling process waits enough period
+ * for all handlers finished. IOW, the disabling process must wait
+ * RCU sync at least once before returning to its caller.
+ */
trace_probe_unlink(&tk->tp);
+ __unregister_trace_kprobe_async(tk);
return 0;
}
@@ -928,11 +964,7 @@ static int create_or_delete_trace_kprobe(int argc, char **argv)
static int trace_kprobe_release(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
- int ret = unregister_trace_kprobe(tk);
-
- if (!ret)
- free_trace_kprobe(tk);
- return ret;
+ return unregister_trace_kprobe(tk);
}
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
next prev parent reply other threads:[~2020-01-16 14:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 14:44 [RFT PATCH 00/13] tracing: kprobes: Introduce async unregistration Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 01/13] kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 02/13] kprobes: Remove redundant arch_disarm_kprobe() call Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 03/13] kprobes: Postpone optimizer until a bunch of probes (un)registered Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 04/13] kprobes: Make optimizer delay to 1 second Masami Hiramatsu
2020-01-22 0:29 ` Steven Rostedt
2020-01-22 7:23 ` Masami Hiramatsu
2020-01-22 12:11 ` Steven Rostedt
2020-01-22 13:12 ` Masami Hiramatsu
2020-01-22 16:54 ` Paul E. McKenney
2020-01-23 1:33 ` Masami Hiramatsu
2020-01-23 2:26 ` Paul E. McKenney
2020-01-23 6:13 ` Masami Hiramatsu
2020-01-23 10:03 ` Paul E. McKenney
2020-01-16 14:45 ` [RFT PATCH 05/13] tracing/kprobe: Use call_rcu to defer freeing event_file_link Masami Hiramatsu
2020-01-27 15:02 ` kbuild test robot
2020-01-27 15:02 ` [RFC PATCH] tracing/kprobe: trace_kprobe_disabled_finished can be static kbuild test robot
2020-01-28 15:02 ` Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 06/13] kprobes: Enable kprobe-booster with CONFIG_PREEMPT=y Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 07/13] kprobes: Use normal list traversal API if a mutex is held Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 08/13] kprobes: Use workqueue for reclaiming kprobe insn cache pages Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 09/13] kprobes: Free kprobe_insn_page asynchronously Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 10/13] kprobes: Make free_*insn_slot() mutex-less Masami Hiramatsu
2020-01-16 14:46 ` [RFT PATCH 11/13] kprobes: Add asynchronous unregistration APIs Masami Hiramatsu
2020-01-16 14:46 ` Masami Hiramatsu [this message]
2020-01-16 14:46 ` [RFT PATCH 13/13] tracing/kprobe: perf_event: Remove local kprobe event asynchronously Masami Hiramatsu
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