linux-kernel - Re: [RFC][PATCH] tracepoints: Free early tracepoints after RCU is initialized

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Message-ID: <20180810123517.5e9714ad@gandalf.local.home>
Date:   Fri, 10 Aug 2018 12:35:17 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Joel Fernandes <joel@...lfernandes.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC][PATCH] tracepoints: Free early tracepoints after RCU is
 initialized

On Fri, 10 Aug 2018 12:30:42 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

Maybe I should say SRCU?

+/* SRCU is initialized at core_initcall */
+postcore_initcall(release_early_probes);
+
 static inline void release_probes(struct tracepoint_func *old)
 {
 	if (old) {
 		struct tp_probes *tp_probes = container_of(old,
 			struct tp_probes, probes[0]);
+
+		/*
+		 * We can't free probes if SRCU is not initialized yet.
+		 * Postpone the freeing till after SRCU is initialized.
+		 */
+		if (unlikely(!ok_to_free_tracepoints)) {
+			tp_probes->rcu.next = early_probes;
+			early_probes = &tp_probes->rcu;
+			return;
+		}
+

-- Steve