Add __string_from_user

[lttng-modules.git] / probes / lttng-ftrace.c

diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
index f583ab6ee9afd2c1d25cd23a657345f07e082137..1aa71831e86fd4bd21780278bb78d385f79ebc8b 100644 (file)
--- a/probes/lttng-ftrace.c
+++ b/probes/lttng-ftrace.c
@@ -11,6 +11,10 @@
  * Ftrace function tracer does not seem to provide synchronization between probe
  * teardown and callback execution. Therefore, we make this module permanently
  * loaded (unloadable).
+ *
+ * TODO: Move to register_ftrace_function() (which is exported for
+ * modules) for Linux >= 3.0. It is faster (only enables the selected
+ * functions), and will stay there.
  */
 
 #include <linux/module.h>
@@ -34,11 +38,16 @@ void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data
        } payload;
        int ret;
 
-       if (!ACCESS_ONCE(chan->session->active))
+       if (unlikely(!ACCESS_ONCE(chan->session->active)))
+               return;
+       if (unlikely(!ACCESS_ONCE(chan->enabled)))
                return;
-       lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL,
+       if (unlikely(!ACCESS_ONCE(event->enabled)))
+               return;
+
+       lib_ring_buffer_ctx_init(&ctx, chan->chan, event,
                                 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;
@@ -78,7 +87,7 @@ int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
        fields[0].type.atype = atype_integer;
        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.signedness = is_signed_type(unsigned long);
        fields[0].type.u.basic.integer.reverse_byte_order = 0;
        fields[0].type.u.basic.integer.base = 16;
        fields[0].type.u.basic.integer.encoding = lttng_encode_none;
@@ -87,11 +96,12 @@ int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
        fields[1].type.atype = atype_integer;
        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.signedness = is_signed_type(unsigned long);
        fields[1].type.u.basic.integer.reverse_byte_order = 0;
        fields[1].type.u.basic.integer.base = 16;
        fields[1].type.u.basic.integer.encoding = lttng_encode_none;
 
+       desc->owner = THIS_MODULE;
        event->desc = desc;
 
        return 0;
@@ -118,7 +128,7 @@ 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;
 
@@ -127,7 +137,7 @@ int lttng_ftrace_register(const char *name,
 
        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;
 
@@ -145,14 +155,18 @@ void lttng_ftrace_unregister(struct ltt_event *event)
 {
        wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
                        &lttng_ftrace_ops, event);
+}
+EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
+
+void lttng_ftrace_destroy_private(struct ltt_event *event)
+{
        kfree(event->u.ftrace.symbol_name);
-       kfree(desc->fields);
+       kfree(event->desc->fields);
        kfree(event->desc->name);
        kfree(event->desc);
 }
-EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
+EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private);
 
-/* This module is permanent. */
 int lttng_ftrace_init(void)
 {
        wrapper_vmalloc_sync_all();
@@ -160,6 +174,15 @@ int lttng_ftrace_init(void)
 }
 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");