From abc0cb0becbacba12ae7f5bf89230af1998cacdd Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 4 Jul 2013 15:46:20 -0400
Subject: [PATCH] Fix printk instrumentation

- Don't require 2kB of stack anymore (requiring so much kernel stack
  space should be considered as a bug in itself),
- Add support for 3.10 kernel printk instrumentation.

This patch uses "Introduce __dynamic_array_enc_ext_2() and
tp_memcpy_dyn_2()".

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 instrumentation/events/lttng-module/printk.h | 87 ++++++++++++--------
 1 file changed, 53 insertions(+), 34 deletions(-)

diff --git a/instrumentation/events/lttng-module/printk.h b/instrumentation/events/lttng-module/printk.h
index 4c744f99..9ac55c72 100644
--- a/instrumentation/events/lttng-module/printk.h
+++ b/instrumentation/events/lttng-module/printk.h
@@ -7,7 +7,25 @@
 #include <linux/tracepoint.h>
 #include <linux/version.h>
 
-#define MSG_TRACE_MAX_LEN	2048
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0))
+
+TRACE_EVENT(console,
+	TP_PROTO(const char *text, size_t len),
+
+	TP_ARGS(text, len),
+
+	TP_STRUCT__entry(
+		__dynamic_array_text(char, msg, len)
+	),
+
+	TP_fast_assign(
+		tp_memcpy_dyn(msg, text)
+	),
+
+	TP_printk("%s", __get_str(msg))
+)
+
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0))
 
 TRACE_EVENT_CONDITION(console,
 	TP_PROTO(const char *log_buf, unsigned start, unsigned end,
@@ -18,46 +36,47 @@ TRACE_EVENT_CONDITION(console,
 	TP_CONDITION(start != end),
 
 	TP_STRUCT__entry(
-		__dynamic_array_text(char, msg,
-			min_t(unsigned, end - start, MSG_TRACE_MAX_LEN) + 1)
+		__dynamic_array_text(char, msg, end - start)
 	),
 
 	TP_fast_assign(
-		tp_memcpy_dyn(msg,
-			({
-				char lmsg[MSG_TRACE_MAX_LEN + 1];
-
-				if ((end - start) > MSG_TRACE_MAX_LEN)
-					start = end - MSG_TRACE_MAX_LEN;
-
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0))
-				if ((start & (log_buf_len - 1)) >
-					(end & (log_buf_len - 1))) {
-					memcpy(lmsg,
-						log_buf +
-						(start & (log_buf_len - 1)),
-						log_buf_len -
-						(start & (log_buf_len - 1)));
-					memcpy(lmsg + log_buf_len -
-						(start & (log_buf_len - 1)),
-						log_buf,
-						end & (log_buf_len - 1));
-				} else
-					memcpy(lmsg,
-						log_buf +
-						(start & (log_buf_len - 1)),
-						end - start);
-#else
-				memcpy(lmsg, log_buf + start, end - start);
-#endif
-				lmsg[end - start] = 0;
-				lmsg;
-			})
-		)
+		tp_memcpy_dyn(msg, log_buf + start)
+	),
+
+	TP_printk("%s", __get_str(msg))
+)
+
+#else /* (LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0)) */
+
+TRACE_EVENT_CONDITION(console,
+	TP_PROTO(const char *log_buf, unsigned start, unsigned end,
+		 unsigned log_buf_len),
+
+	TP_ARGS(log_buf, start, end, log_buf_len),
+
+	TP_CONDITION(start != end),
+
+	TP_STRUCT__entry(
+		__dynamic_array_text_2(char, msg,
+			(start & (log_buf_len - 1)) > (end & (log_buf_len - 1))
+				? log_buf_len - (start & (log_buf_len - 1))
+				: end - start,
+			(start & (log_buf_len - 1)) > (end & (log_buf_len - 1))
+				? end & (log_buf_len - 1)
+				: 0)
+	),
+
+	TP_fast_assign(
+		tp_memcpy_dyn_2(msg,
+			log_buf + (start & (log_buf_len - 1)),
+			log_buf)
 	),
 
 	TP_printk("%s", __get_str(msg))
 )
+
+#endif
+
 #endif /* _TRACE_PRINTK_H */
 
 /* This part must be outside protection */
-- 
2.34.1