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