Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754063AbdIEV7R (ORCPT ); Tue, 5 Sep 2017 17:59:17 -0400 Received: from mga07.intel.com ([134.134.136.100]:64616 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754024AbdIEV7K (ORCPT ); Tue, 5 Sep 2017 17:59:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,481,1498546800"; d="scan'208";a="147850978" From: Tom Zanussi To: rostedt@goodmis.org Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, bigeasy@linutronix.de, joel.opensrc@gmail.com, joelaf@google.com, mathieu.desnoyers@efficios.com, baohong.liu@intel.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Tom Zanussi Subject: [PATCH v2 25/40] tracing: Add support for dynamic tracepoints Date: Tue, 5 Sep 2017 16:57:37 -0500 Message-Id: <9f89af4588c84850a58edcf72d2591ba78906c30.1504642143.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2650 Lines: 79 The tracepoint infrastructure assumes statically-defined tracepoints and uses static_keys for tracepoint enablement. In order to define tracepoints on the fly, we need to have a dynamic counterpart. Add a 'dynamic' flag to struct tracepoint along with accompanying logic for this purpose. Signed-off-by: Tom Zanussi --- include/linux/tracepoint-defs.h | 1 + kernel/tracepoint.c | 18 +++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h index a031920..bc22d54 100644 --- a/include/linux/tracepoint-defs.h +++ b/include/linux/tracepoint-defs.h @@ -32,6 +32,7 @@ struct tracepoint { int (*regfunc)(void); void (*unregfunc)(void); struct tracepoint_func __rcu *funcs; + bool dynamic; }; #endif diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 685c50a..1c5957f 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -197,7 +197,9 @@ static int tracepoint_add_func(struct tracepoint *tp, struct tracepoint_func *old, *tp_funcs; int ret; - if (tp->regfunc && !static_key_enabled(&tp->key)) { + if (tp->regfunc && + ((tp->dynamic && !(atomic_read(&tp->key.enabled) > 0)) || + !static_key_enabled(&tp->key))) { ret = tp->regfunc(); if (ret < 0) return ret; @@ -219,7 +221,9 @@ static int tracepoint_add_func(struct tracepoint *tp, * is used. */ rcu_assign_pointer(tp->funcs, tp_funcs); - if (!static_key_enabled(&tp->key)) + if (tp->dynamic && !(atomic_read(&tp->key.enabled) > 0)) + atomic_inc(&tp->key.enabled); + else if (!tp->dynamic && !static_key_enabled(&tp->key)) static_key_slow_inc(&tp->key); release_probes(old); return 0; @@ -246,10 +250,14 @@ static int tracepoint_remove_func(struct tracepoint *tp, if (!tp_funcs) { /* Removed last function */ - if (tp->unregfunc && static_key_enabled(&tp->key)) + if (tp->unregfunc && + ((tp->dynamic && (atomic_read(&tp->key.enabled) > 0)) || + static_key_enabled(&tp->key))) tp->unregfunc(); - if (static_key_enabled(&tp->key)) + if (tp->dynamic && (atomic_read(&tp->key.enabled) > 0)) + atomic_dec(&tp->key.enabled); + else if (!tp->dynamic && static_key_enabled(&tp->key)) static_key_slow_dec(&tp->key); } rcu_assign_pointer(tp->funcs, tp_funcs); @@ -258,7 +266,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, } /** - * tracepoint_probe_register - Connect a probe to a tracepoint + * tracepoint_probe_register_prio - Connect a probe to a tracepoint * @tp: tracepoint * @probe: probe handler * @data: tracepoint data -- 1.9.3