[PATCH 4/4] libtracefs: Have tracefs_cpu_flush(_buf)() use mapping

[Steven Rostedt <rostedt@goodmis.org>]

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

If the tracefs_cpu is opened with tracefs_cpu_open_mapped() and uses
tracefs_cpu_read_buf() along with tracefs_cpu_flush_buf(), the flush will
load the tcpu->kbuf with a new buffer which may make the one in the mmapped
out of sync.

If the tcpu is mapped, make sure tracefs_cpu_flush() and
tracefs_cpu_flush_buf() also use the mapping.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 src/tracefs-record.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/tracefs-record.c b/src/tracefs-record.c
index 4a59c61c195f..fca3ddf9afbe 100644
--- a/src/tracefs-record.c
+++ b/src/tracefs-record.c
@@ -690,6 +690,9 @@ int tracefs_cpu_flush(struct tracefs_cpu *tcpu, void *buffer)
 	if (tcpu->buffered < 0)
 		tcpu->buffered = 0;
 
+	if (tcpu->mapping)
+		return trace_mmap_read(tcpu->mapping, buffer);
+
 	if (tcpu->buffered) {
 		ret = read(tcpu->splice_pipe[0], buffer, tcpu->subbuf_size);
 		if (ret > 0)
@@ -729,6 +732,13 @@ struct kbuffer *tracefs_cpu_flush_buf(struct tracefs_cpu *tcpu)
 	if (!get_buffer(tcpu))
 		return NULL;
 
+	if (tcpu->mapping) {
+		/* Make sure that reading is now non blocking */
+		set_nonblock(tcpu);
+		ret = trace_mmap_load_subbuf(tcpu->mapping, tcpu->kbuf);
+		return ret > 0 ? tcpu->kbuf : NULL;
+	}
+
 	ret = tracefs_cpu_flush(tcpu, tcpu->buffer);
 	if (ret <= 0)
 		return NULL;
-- 
2.43.0