[for-next][PATCH 05/10] tracing: Have trace_marker break up by lines by size of trace_seq

[Steven Rostedt]

From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>

If a trace_marker write is bigger than what trace_seq can hold, then it
will print "LINE TOO BIG" message and not what was written.

Instead, check if the write is bigger than the trace_seq and break it
up by that size.

Ideally, we could make the trace_seq dynamic that could hold this. But
that's for another time.

Link: https://lore.kernel.org/linux-trace-kernel/20231212190422.1eaf224f@xxxxxxxxxxxxxxxxxx

Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0be30cccabb4..9cf58383d2fb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7304,6 +7304,11 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	if (cnt < FAULTED_SIZE)
 		size += FAULTED_SIZE - cnt;
 
+	if (size > TRACE_SEQ_BUFFER_SIZE) {
+		cnt -= size - TRACE_SEQ_BUFFER_SIZE;
+		goto again;
+	}
+
 	buffer = tr->array_buffer.buffer;
 	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
 					    tracing_gen_ctx());
-- 
2.42.0