From 8fefc8a2d93a06a032c7983cf621ab3fb0c2acde Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 1 Jun 2011 14:22:50 -0400
Subject: [PATCH] Add task_prio symbol wrapper

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 Makefile             |  3 ++-
 ltt-events.c         |  3 +++
 ltt-events.h         |  4 ++++
 lttng-context-prio.c |  2 +-
 wrapper/sched.c      | 22 ++++++++++++++++++++++
 wrapper/sched.h      | 32 ++++++++++++++++++++++++++++++++
 6 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 wrapper/sched.c
 create mode 100644 wrapper/sched.h

diff --git a/Makefile b/Makefile
index fa337a0f..62698b2a 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,8 @@ obj-m += ltt-relay.o
 ltt-relay-objs :=  ltt-events.o ltt-debugfs-abi.o \
 			ltt-probes.o ltt-core.o ltt-context.o \
 			lttng-context-pid.o lttng-context-comm.o \
-			lttng-context-prio.o lttng-context-nice.o
+			lttng-context-prio.o lttng-context-nice.o \
+			wrapper/sched.o
 
 obj-m += probes/
 obj-m += lib/
diff --git a/ltt-events.c b/ltt-events.c
index f98ef309..7c08def9 100644
--- a/ltt-events.c
+++ b/ltt-events.c
@@ -860,6 +860,9 @@ static int __init ltt_events_init(void)
 {
 	int ret;
 
+	ret = wrapper_task_prio_init();
+	if (ret)
+		return ret;
 	event_cache = KMEM_CACHE(ltt_event, 0);
 	if (!event_cache)
 		return -ENOMEM;
diff --git a/ltt-events.h b/ltt-events.h
index b9bb3bb9..975d1949 100644
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -272,6 +272,10 @@ int ltt_probes_init(void);
 void ltt_probes_exit(void);
 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx);
 void lttng_destroy_context(struct lttng_ctx *ctx);
+
+int wrapper_task_prio_init(void);
+int wrapper_task_prio_sym(struct task_struct *t);
+
 int lttng_add_pid_to_ctx(struct lttng_ctx **ctx);
 int lttng_add_comm_to_ctx(struct lttng_ctx **ctx);
 int lttng_add_prio_to_ctx(struct lttng_ctx **ctx);
diff --git a/lttng-context-prio.c b/lttng-context-prio.c
index c8f83f48..a62685f7 100644
--- a/lttng-context-prio.c
+++ b/lttng-context-prio.c
@@ -32,7 +32,7 @@ void prio_record(struct lttng_ctx_field *field,
 {
 	int prio;
 
-	prio = task_prio(current);
+	prio = wrapper_task_prio_sym(current);
 	lib_ring_buffer_align_ctx(ctx, ltt_alignof(prio));
 	chan->ops->event_write(ctx, &prio, sizeof(prio));
 }
diff --git a/wrapper/sched.c b/wrapper/sched.c
new file mode 100644
index 00000000..229dc075
--- /dev/null
+++ b/wrapper/sched.c
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * Wrapper around task_prio call.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/kallsyms.h>
+#include <linux/sched.h>
+
+void (*wrapper_task_prio_sym)(struct task_struct *t);
+
+int wrapper_task_prio_init(void)
+{
+	wrapper_task_prio_sym = (void *) kallsyms_lookup_name("task_prio");
+	if (!wrapper_task_prio_sym) {
+		printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
+		return -EINVAL;
+	}
+	return 0;
+}
diff --git a/wrapper/sched.h b/wrapper/sched.h
new file mode 100644
index 00000000..1332cfe6
--- /dev/null
+++ b/wrapper/sched.h
@@ -0,0 +1,32 @@
+#ifndef _LTT_WRAPPER_VMALLOC_H
+#define _LTT_WRAPPER_VMALLOC_H
+
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * Wrapper around task_prio call.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#ifdef CONFIG_KALLSYMS
+
+#include "../ltt-events.h"
+
+static inline
+int wrapper_task_prio(struct task_struct *t)
+{
+	return wrapper_task_prio_sym(t);
+}
+#else
+
+#include <linux/sched.h>
+
+static inline
+int wrapper_task_prio(struct task_struct *t)
+{
+	return task_prio(t);
+}
+#endif
+
+#endif /* _LTT_WRAPPER_VMALLOC_H */
-- 
2.34.1