printk/tracing: rework console tracing

Commit 7ff9554 ("printk: convert byte-buffer to variable-length
record buffer") removed start and end parameters from
call_console_drivers, but those parameters still exist in
include/trace/events/printk.h.

Without start and end parameters handling, printk tracing became more
simple as: trace_console(text, len);

Signed-off-by: zhangwei(Jovi) <[email protected]>
Acked-by: Steven Rostedt <[email protected]>
Acked-by: Frederic Weisbecker <[email protected]>
Cc: Kay Sievers <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: zhangwei(Jovi)

include/trace/events/printk.h

@@ -6,31 +6,18 @@
 
 #include <linux/tracepoint.h>
 
-TRACE_EVENT_CONDITION(console,
-	TP_PROTO(const char *log_buf, unsigned start, unsigned end,
-		 unsigned log_buf_len),
+TRACE_EVENT(console,
+	TP_PROTO(const char *text, size_t len),
 
-	TP_ARGS(log_buf, start, end, log_buf_len),
-
-	TP_CONDITION(start != end),
+	TP_ARGS(text, len),
 
 	TP_STRUCT__entry(
-		__dynamic_array(char, msg, end - start + 1)
+		__dynamic_array(char, msg, len + 1)
 	),
 
 	TP_fast_assign(
-		if ((start & (log_buf_len - 1)) > (end & (log_buf_len - 1))) {
-			memcpy(__get_dynamic_array(msg),
-			       log_buf + (start & (log_buf_len - 1)),
-			       log_buf_len - (start & (log_buf_len - 1)));
-			memcpy((char *)__get_dynamic_array(msg) +
-			       log_buf_len - (start & (log_buf_len - 1)),
-			       log_buf, end & (log_buf_len - 1));
-		} else
-			memcpy(__get_dynamic_array(msg),
-			       log_buf + (start & (log_buf_len - 1)),
-			       end - start);
-		((char *)__get_dynamic_array(msg))[end - start] = 0;
+		memcpy(__get_dynamic_array(msg), text, len);
+		((char *)__get_dynamic_array(msg))[len] = 0;
 	),
 
 	TP_printk("%s", __get_str(msg))

kernel/printk.c

@@ -1265,7 +1265,7 @@ static void call_console_drivers(int level, const char *text, size_t len)
 {
 	struct console *con;
 
-	trace_console(text, 0, len, len);
+	trace_console(text, len);
 
 	if (level >= console_loglevel && !ignore_loglevel)
 		return;