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Subject[RFC patch 22/41] LTTng marker control
Marker control. Depends on LTT to assign numeric IDs to markers. Used by the
following ltt trace control module which exports these interfaces through
debugfs.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Jan Kiszka <jan.kiszka@siemens.com>
---
ltt/ltt-marker-control.c | 265 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 265 insertions(+)
Index: linux-2.6-lttng/ltt/ltt-marker-control.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-lttng/ltt/ltt-marker-control.c 2009-02-06 18:15:14.000000000 -0500
@@ -0,0 +1,265 @@
+/*
+ * Copyright (C) 2007 Mathieu Desnoyers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/stat.h>
+#include <linux/vmalloc.h>
+#include <linux/marker.h>
+#include <linux/ltt-tracer.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+
+#define DEFAULT_CHANNEL "cpu"
+#define DEFAULT_PROBE "default"
+
+LIST_HEAD(probes_list);
+
+/*
+ * Mutex protecting the probe slab cache.
+ * Nests inside the traces mutex.
+ */
+DEFINE_MUTEX(probes_mutex);
+
+struct ltt_available_probe default_probe = {
+ .name = "default",
+ .format = NULL,
+ .probe_func = ltt_vtrace,
+ .callbacks[0] = ltt_serialize_data,
+};
+
+static struct kmem_cache *markers_loaded_cachep;
+static LIST_HEAD(markers_loaded_list);
+/*
+ * List sorted by name strcmp order.
+ */
+static LIST_HEAD(probes_registered_list);
+
+static struct ltt_available_probe *get_probe_from_name(const char *pname)
+{
+ struct ltt_available_probe *iter;
+ int comparison, found = 0;
+
+ if (!pname)
+ pname = DEFAULT_PROBE;
+ list_for_each_entry(iter, &probes_registered_list, node) {
+ comparison = strcmp(pname, iter->name);
+ if (!comparison)
+ found = 1;
+ if (comparison <= 0)
+ break;
+ }
+ if (found)
+ return iter;
+ else
+ return NULL;
+}
+
+int ltt_probe_register(struct ltt_available_probe *pdata)
+{
+ int ret = 0;
+ int comparison;
+ struct ltt_available_probe *iter;
+
+ mutex_lock(&probes_mutex);
+ list_for_each_entry_reverse(iter, &probes_registered_list, node) {
+ comparison = strcmp(pdata->name, iter->name);
+ if (!comparison) {
+ ret = -EBUSY;
+ goto end;
+ } else if (comparison > 0) {
+ /* We belong to the location right after iter. */
+ list_add(&pdata->node, &iter->node);
+ goto end;
+ }
+ }
+ /* Should be added at the head of the list */
+ list_add(&pdata->node, &probes_registered_list);
+end:
+ mutex_unlock(&probes_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_register);
+
+/*
+ * Called when a probe does not want to be called anymore.
+ */
+int ltt_probe_unregister(struct ltt_available_probe *pdata)
+{
+ int ret = 0;
+ struct ltt_active_marker *amark, *tmp;
+
+ mutex_lock(&probes_mutex);
+ list_for_each_entry_safe(amark, tmp, &markers_loaded_list, node) {
+ if (amark->probe == pdata) {
+ ret = marker_probe_unregister_private_data(
+ pdata->probe_func, amark);
+ if (ret)
+ goto end;
+ list_del(&amark->node);
+ kmem_cache_free(markers_loaded_cachep, amark);
+ }
+ }
+ list_del(&pdata->node);
+end:
+ mutex_unlock(&probes_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_unregister);
+
+/*
+ * Connect marker "mname" to probe "pname".
+ * Only allow _only_ probe instance to be connected to a marker.
+ */
+int ltt_marker_connect(const char *channel, const char *mname,
+ const char *pname)
+
+{
+ int ret;
+ struct ltt_active_marker *pdata;
+ struct ltt_available_probe *probe;
+
+ ltt_lock_traces();
+ mutex_lock(&probes_mutex);
+ probe = get_probe_from_name(pname);
+ if (!probe) {
+ ret = -ENOENT;
+ goto end;
+ }
+ pdata = marker_get_private_data(channel, mname, probe->probe_func, 0);
+ if (pdata && !IS_ERR(pdata)) {
+ ret = -EEXIST;
+ goto end;
+ }
+ pdata = kmem_cache_zalloc(markers_loaded_cachep, GFP_KERNEL);
+ if (!pdata) {
+ ret = -ENOMEM;
+ goto end;
+ }
+ pdata->probe = probe;
+ /*
+ * ID has priority over channel in case of conflict.
+ */
+ ret = marker_probe_register(channel, mname, NULL,
+ probe->probe_func, pdata);
+ if (ret)
+ kmem_cache_free(markers_loaded_cachep, pdata);
+ else
+ list_add(&pdata->node, &markers_loaded_list);
+end:
+ mutex_unlock(&probes_mutex);
+ ltt_unlock_traces();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_marker_connect);
+
+/*
+ * Disconnect marker "mname", probe "pname".
+ */
+int ltt_marker_disconnect(const char *channel, const char *mname,
+ const char *pname)
+{
+ struct ltt_active_marker *pdata;
+ struct ltt_available_probe *probe;
+ int ret = 0;
+
+ mutex_lock(&probes_mutex);
+ probe = get_probe_from_name(pname);
+ if (!probe) {
+ ret = -ENOENT;
+ goto end;
+ }
+ pdata = marker_get_private_data(channel, mname, probe->probe_func, 0);
+ if (IS_ERR(pdata)) {
+ ret = PTR_ERR(pdata);
+ goto end;
+ } else if (!pdata) {
+ /*
+ * Not registered by us.
+ */
+ ret = -EPERM;
+ goto end;
+ }
+ ret = marker_probe_unregister(channel, mname, probe->probe_func, pdata);
+ if (ret)
+ goto end;
+ else {
+ list_del(&pdata->node);
+ kmem_cache_free(markers_loaded_cachep, pdata);
+ }
+end:
+ mutex_unlock(&probes_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_marker_disconnect);
+
+static void disconnect_all_markers(void)
+{
+ struct ltt_active_marker *pdata, *tmp;
+
+ list_for_each_entry_safe(pdata, tmp, &markers_loaded_list, node) {
+ marker_probe_unregister_private_data(pdata->probe->probe_func,
+ pdata);
+ list_del(&pdata->node);
+ kmem_cache_free(markers_loaded_cachep, pdata);
+ }
+}
+
+static int __init marker_control_init(void)
+{
+ int ret;
+
+ markers_loaded_cachep = KMEM_CACHE(ltt_active_marker, 0);
+
+ ret = ltt_probe_register(&default_probe);
+ BUG_ON(ret);
+ ret = ltt_marker_connect("metadata", "core_marker_format",
+ DEFAULT_PROBE);
+ BUG_ON(ret);
+ ret = ltt_marker_connect("metadata", "core_marker_id", DEFAULT_PROBE);
+ BUG_ON(ret);
+
+ return 0;
+}
+module_init(marker_control_init);
+
+static void __exit marker_control_exit(void)
+{
+ int ret;
+
+ ret = ltt_marker_disconnect("metadata", "core_marker_format",
+ DEFAULT_PROBE);
+ BUG_ON(ret);
+ ret = ltt_marker_disconnect("metadata", "core_marker_id",
+ DEFAULT_PROBE);
+ BUG_ON(ret);
+ ret = ltt_probe_unregister(&default_probe);
+ BUG_ON(ret);
+ disconnect_all_markers();
+ kmem_cache_destroy(markers_loaded_cachep);
+ marker_synchronize_unregister();
+}
+module_exit(marker_control_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Marker Control");
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


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