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[209.132.180.67]) by mx.google.com with ESMTP id 62si5785859ply.308.2016.11.23.07.38.45; Wed, 23 Nov 2016 07:38:45 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965405AbcKWPi0 (ORCPT + 25 others); Wed, 23 Nov 2016 10:38:26 -0500 Received: from mail.kernel.org ([198.145.29.136]:60318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965359AbcKWPfd (ORCPT ); Wed, 23 Nov 2016 10:35:33 -0500 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2AB7920425; Wed, 23 Nov 2016 15:35:32 +0000 (UTC) Received: from gandalf.local.home (cpe-67-246-153-56.stny.res.rr.com [67.246.153.56]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0AA2C203F1; Wed, 23 Nov 2016 15:35:30 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.87) (envelope-from ) id 1c9Za5-0001FZ-2z; Wed, 23 Nov 2016 10:35:29 -0500 Message-Id: <20161123153529.019495860@goodmis.org> User-Agent: quilt/0.63-1 Date: Wed, 23 Nov 2016 10:35:23 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Chunyan Zhang Subject: [for-next][PATCH 11/17] tracing: Add hook to function tracing for other subsystems to use References: <20161123153512.923515549@goodmis.org> MIME-Version: 1.0 Content-Disposition: inline; filename=0011-tracing-Add-hook-to-function-tracing-for-other-subsy.patch X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chunyan Zhang Currently Function traces can be only exported to the ring buffer. This adds a trace_export concept which can process traces and export them to a registered destination as an addition to the current one that outputs to Ftrace - i.e. ring buffer. In this way, if we want function traces to be sent to other destinations rather than only to the ring buffer, we just need to register a new trace_export and implement its own .write() function for writing traces to storage. With this patch, only function tracing (trace type is TRACE_FN) is supported. Link: http://lkml.kernel.org/r/1479715043-6534-2-git-send-email-zhang.chunyan@linaro.org Signed-off-by: Chunyan Zhang Signed-off-by: Steven Rostedt --- include/linux/trace.h | 28 +++++++++++ kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 156 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace.h -- 2.10.2 diff --git a/include/linux/trace.h b/include/linux/trace.h new file mode 100644 index 000000000000..9330a58e2651 --- /dev/null +++ b/include/linux/trace.h @@ -0,0 +1,28 @@ +#ifndef _LINUX_TRACE_H +#define _LINUX_TRACE_H + +#ifdef CONFIG_TRACING +/* + * The trace export - an export of Ftrace output. The trace_export + * can process traces and export them to a registered destination as + * an addition to the current only output of Ftrace - i.e. ring buffer. + * + * If you want traces to be sent to some other place rather than ring + * buffer only, just need to register a new trace_export and implement + * its own .write() function for writing traces to the storage. + * + * next - pointer to the next trace_export + * write - copy traces which have been delt with ->commit() to + * the destination + */ +struct trace_export { + struct trace_export __rcu *next; + void (*write)(const void *, unsigned int); +}; + +int register_ftrace_export(struct trace_export *export); +int unregister_ftrace_export(struct trace_export *export); + +#endif /* CONFIG_TRACING */ + +#endif /* _LINUX_TRACE_H */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 57069e7f369c..edccdff8a36d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include "trace.h" @@ -2128,6 +2129,129 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, ftrace_trace_userstack(buffer, flags, pc); } +static void +trace_process_export(struct trace_export *export, + struct ring_buffer_event *event) +{ + struct trace_entry *entry; + unsigned int size = 0; + + entry = ring_buffer_event_data(event); + size = ring_buffer_event_length(event); + export->write(entry, size); +} + +static DEFINE_MUTEX(ftrace_export_lock); + +static struct trace_export __rcu *ftrace_exports_list __read_mostly; + +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); + +static inline void ftrace_exports_enable(void) +{ + static_branch_enable(&ftrace_exports_enabled); +} + +static inline void ftrace_exports_disable(void) +{ + static_branch_disable(&ftrace_exports_enabled); +} + +void ftrace_exports(struct ring_buffer_event *event) +{ + struct trace_export *export; + + preempt_disable_notrace(); + + export = rcu_dereference_raw_notrace(ftrace_exports_list); + while (export) { + trace_process_export(export, event); + export = rcu_dereference_raw_notrace(export->next); + } + + preempt_enable_notrace(); +} + +static inline void +add_trace_export(struct trace_export **list, struct trace_export *export) +{ + rcu_assign_pointer(export->next, *list); + /* + * We are entering export into the list but another + * CPU might be walking that list. We need to make sure + * the export->next pointer is valid before another CPU sees + * the export pointer included into the list. + */ + rcu_assign_pointer(*list, export); +} + +static inline int +rm_trace_export(struct trace_export **list, struct trace_export *export) +{ + struct trace_export **p; + + for (p = list; *p != NULL; p = &(*p)->next) + if (*p == export) + break; + + if (*p != export) + return -1; + + rcu_assign_pointer(*p, (*p)->next); + + return 0; +} + +static inline void +add_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + if (*list == NULL) + ftrace_exports_enable(); + + add_trace_export(list, export); +} + +static inline int +rm_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + int ret; + + ret = rm_trace_export(list, export); + if (*list == NULL) + ftrace_exports_disable(); + + return ret; +} + +int register_ftrace_export(struct trace_export *export) +{ + if (WARN_ON_ONCE(!export->write)) + return -1; + + mutex_lock(&ftrace_export_lock); + + add_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(register_ftrace_export); + +int unregister_ftrace_export(struct trace_export *export) +{ + int ret; + + mutex_lock(&ftrace_export_lock); + + ret = rm_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(unregister_ftrace_export); + void trace_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, @@ -2146,8 +2270,11 @@ trace_function(struct trace_array *tr, entry->ip = ip; entry->parent_ip = parent_ip; - if (!call_filter_check_discard(call, entry, buffer, event)) + if (!call_filter_check_discard(call, entry, buffer, event)) { + if (static_branch_unlikely(&ftrace_exports_enabled)) + ftrace_exports(event); __buffer_unlock_commit(buffer, event); + } } #ifdef CONFIG_STACKTRACE