X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=probes%2Flttng-ftrace.c;h=5b4cf2e7e153c0318e2ca8d485489bd46340e7aa;hb=8a58609868bb8e20dc93478714805e8c3126bd9b;hp=3ec000ae576e8b5adde12b6bb27fc4b408f033fc;hpb=5a9479dcba0b43d326569fa0bd48318222d23fcb;p=lttng-modules.git

diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
index 3ec000ae..5b4cf2e7 100644
--- a/probes/lttng-ftrace.c
+++ b/probes/lttng-ftrace.c
@@ -7,12 +7,19 @@
  * Dual LGPL v2.1/GPL v2 license.
  */
 
+/*
+ * Ftrace function tracer does not seem to provide synchronization between probe
+ * teardown and callback execution. Therefore, we make this module permanently
+ * loaded (unloadable).
+ */
+
 #include <linux/module.h>
 #include <linux/ftrace.h>
 #include <linux/slab.h>
 #include "../ltt-events.h"
 #include "../wrapper/ringbuffer/frontend_types.h"
 #include "../wrapper/ftrace.h"
+#include "../wrapper/vmalloc.h"
 #include "../ltt-tracer.h"
 
 static
@@ -31,7 +38,7 @@ void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data
 		return;
 	lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL,
 				 sizeof(payload), ltt_alignof(payload), -1);
-	ret = chan->ops->event_reserve(&ctx);
+	ret = chan->ops->event_reserve(&ctx, event->id);
 	if (ret < 0)
 		return;
 	payload.ip = ip;
@@ -63,10 +70,14 @@ int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
 	desc->nr_fields = 2;
 	desc->fields = fields =
 		kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
+	if (!desc->fields) {
+		ret = -ENOMEM;
+		goto error_fields;
+	}
 	fields[0].name = "ip";
 	fields[0].type.atype = atype_integer;
-	fields[0].type.u.basic.integer.size = sizeof(unsigned long);
-	fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long);
+	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
 	fields[0].type.u.basic.integer.signedness = 0;
 	fields[0].type.u.basic.integer.reverse_byte_order = 0;
 	fields[0].type.u.basic.integer.base = 16;
@@ -74,8 +85,8 @@ int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
 
 	fields[1].name = "parent_ip";
 	fields[1].type.atype = atype_integer;
-	fields[1].type.u.basic.integer.size = sizeof(unsigned long);
-	fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long);
+	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
 	fields[1].type.u.basic.integer.signedness = 0;
 	fields[1].type.u.basic.integer.reverse_byte_order = 0;
 	fields[1].type.u.basic.integer.base = 16;
@@ -85,6 +96,8 @@ int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
 
 	return 0;
 
+error_fields:
+	kfree(desc->name);
 error_str:
 	kfree(desc);
 	return ret;
@@ -105,13 +118,16 @@ int lttng_ftrace_register(const char *name,
 	if (ret)
 		goto error;
 
-	event->u.ftrace.symbol_name = kstrdup(name, GFP_KERNEL);
+	event->u.ftrace.symbol_name = kstrdup(symbol_name, GFP_KERNEL);
 	if (!event->u.ftrace.symbol_name)
 		goto name_error;
 
+	/* Ensure the memory we just allocated don't trigger page faults */
+	wrapper_vmalloc_sync_all();
+
 	ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
 			&lttng_ftrace_ops, event);
-	if (ret)
+	if (ret < 0)
 		goto register_error;
 	return 0;
 
@@ -130,11 +146,28 @@ void lttng_ftrace_unregister(struct ltt_event *event)
 	wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
 			&lttng_ftrace_ops, event);
 	kfree(event->u.ftrace.symbol_name);
+	kfree(event->desc->fields);
 	kfree(event->desc->name);
 	kfree(event->desc);
 }
 EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
 
+int lttng_ftrace_init(void)
+{
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+module_init(lttng_ftrace_init)
+
+/*
+ * Ftrace takes care of waiting for a grace period (RCU sched) at probe
+ * unregistration, and disables preemption around probe call.
+ */
+void lttng_ftrace_exit(void)
+{
+}
+module_exit(lttng_ftrace_exit)
+
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers");
 MODULE_DESCRIPTION("Linux Trace Toolkit Ftrace Support");