Fix ftrace support

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
index 4b7be18336c07d8b8eecd1f745a64da00a6ebc7a..3ec000ae576e8b5adde12b6bb27fc4b408f033fc 100644 (file)
--- a/probes/lttng-ftrace.c
+++ b/probes/lttng-ftrace.c
@@ -12,10 +12,11 @@
 #include <linux/slab.h>
 #include "../ltt-events.h"
 #include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/ftrace.h"
 #include "../ltt-tracer.h"
 
 static
-int lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
+void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
 {
        struct ltt_event *event = *data;
        struct ltt_channel *chan = event->chan;
@@ -27,18 +28,18 @@ int lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
        int ret;
 
        if (!ACCESS_ONCE(chan->session->active))
-               return 0;
+               return;
        lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL,
                                 sizeof(payload), ltt_alignof(payload), -1);
        ret = chan->ops->event_reserve(&ctx);
        if (ret < 0)
-               return 0;
+               return;
        payload.ip = ip;
        payload.parent_ip = parent_ip;
        lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload));
        chan->ops->event_write(&ctx, &payload, sizeof(payload));
        chan->ops->event_commit(&ctx);
-       return 0;
+       return;
 }
 
 /*
@@ -108,7 +109,7 @@ int lttng_ftrace_register(const char *name,
        if (!event->u.ftrace.symbol_name)
                goto name_error;
 
-       ret = register_ftrace_function_probe(symbol_name,
+       ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
                        &lttng_ftrace_ops, event);
        if (ret)
                goto register_error;
@@ -126,7 +127,7 @@ EXPORT_SYMBOL_GPL(lttng_ftrace_register);
 
 void lttng_ftrace_unregister(struct ltt_event *event)
 {
-       unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
+       wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
                        &lttng_ftrace_ops, event);
        kfree(event->u.ftrace.symbol_name);
        kfree(event->desc->name);

diff --git a/wrapper/ftrace.h b/wrapper/ftrace.h
new file mode 100644 (file)
index 0000000..4401469
--- /dev/null
+++ b/wrapper/ftrace.h
@@ -0,0 +1,70 @@
+#ifndef _LTT_WRAPPER_FTRACE_H
+#define _LTT_WRAPPER_FTRACE_H
+
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * wrapper around vmalloc_sync_all. Using KALLSYMS to get its address when
+ * available, else we need to have a kernel that exports this function to GPL
+ * modules.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/ftrace.h>
+
+#ifdef CONFIG_KALLSYMS
+
+#include <linux/kallsyms.h>
+
+static inline
+int wrapper_register_ftrace_function_probe(char *glob,
+               struct ftrace_probe_ops *ops, void *data)
+{
+       int (*register_ftrace_function_probe_sym)(char *glob,
+                       struct ftrace_probe_ops *ops, void *data);
+
+       register_ftrace_function_probe_sym = (void *) kallsyms_lookup_name("register_ftrace_function_probe_sym");
+       if (register_ftrace_function_probe_sym) {
+               return register_ftrace_function_probe_sym(glob, ops, data);
+       } else {
+               printk(KERN_WARNING "LTTng: register_ftrace_function_probe symbol lookup failed.\n");
+               return -EINVAL;
+       }
+}
+
+static inline
+void wrapper_unregister_ftrace_function_probe(char *glob,
+               struct ftrace_probe_ops *ops, void *data)
+{
+       void (*unregister_ftrace_function_probe_sym)(char *glob,
+                       struct ftrace_probe_ops *ops, void *data);
+
+       unregister_ftrace_function_probe_sym = (void *) kallsyms_lookup_name("unregister_ftrace_function_probe_sym");
+       if (unregister_ftrace_function_probe_sym) {
+               unregister_ftrace_function_probe_sym(glob, ops, data);
+       } else {
+               printk(KERN_WARNING "LTTng: unregister_ftrace_function_probe symbol lookup failed.\n");
+               WARN_ON(1);
+       }
+}
+
+#else
+
+static inline
+int wrapper_register_ftrace_function_probe(char *glob,
+               struct ftrace_probe_ops *ops, void *data);
+
+{
+       return unregister_ftrace_function_probe();
+}
+
+static inline
+void wrapper_unregister_ftrace_function_probe(char *glob,
+               struct ftrace_probe_ops *ops, void *data);
+{
+       return unregister_ftrace_function_probe();
+}
+#endif
+
+#endif /* _LTT_WRAPPER_FTRACE_H */