trace-cmd: Use splice to filter out rest of buffer

When the main thread tells the recorders that they are finished,
have the recorders still use splice till all data is read that
splice can handle (full page sizes only). Then use the read function
for the rest.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 40 insertions, 14 deletions

diff --git a/trace-recorder.c b/trace-recorder.c
index 2a754b9..e57ef9b 100644
--- a/trace-recorder.c
+++ b/trace-recorder.c
@@ -128,11 +128,39 @@ struct tracecmd_recorder *tracecmd_create_recorder(const char *file, int cpu)
         return recorder;
 }
 
+/*
+ * Returns -1 on error.
+ *          or bytes of data read.
+ */
+static long splice_data(struct tracecmd_recorder *recorder)
+{
+        long ret;
+
+        ret = splice(recorder->trace_fd, NULL, recorder->brass[1], NULL,
+                     recorder->page_size, 1 /* SPLICE_F_MOVE */);
+        if (ret < 0) {
+                warning("recorder error in splice input");
+                return -1;
+        }
+
+        ret = splice(recorder->brass[0], NULL, recorder->fd, NULL,
+                     recorder->page_size, 3 /* and NON_BLOCK */);
+        if (ret < 0) {
+                if (errno != EAGAIN) {
+                        warning("recorder error in splice output");
+                        return -1;
+                }
+                ret = 0;
+        }
+
+        return ret;
+}
+
 int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long sleep)
 {
         struct timespec req;
         char *buf[recorder->page_size];
-        int ret;
+        long ret;
 
         recorder->stop = 0;
 
@@ -142,21 +170,19 @@ int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long s
                         req.tv_nsec = (sleep % 1000000) * 1000;
                         nanosleep(&req, NULL);
                 }
-
-                ret = splice(recorder->trace_fd, NULL, recorder->brass[1], NULL,
-                             recorder->page_size, 1 /* SPLICE_F_MOVE */);
-                if (ret < 0) {
-                        warning("recorder error in splice input");
-                        return -1;
-                }
-                ret = splice(recorder->brass[0], NULL, recorder->fd, NULL,
-                             recorder->page_size, 3 /* and NON_BLOCK */);
-                if (ret < 0 && errno != EAGAIN) {
-                        warning("recorder error in splice output");
-                        return -1;
-                }
+                ret = splice_data(recorder);
+                if (ret < 0)
+                        return ret;
         } while (!recorder->stop);
 
+        /* Flush via splice first */
+        do {
+                ret = splice_data(recorder);
+        } while (ret > 0);
+
+        if (ret < 0)
+                return ret;
+
         /* splice only reads full pages */
         do {
                 ret = read(recorder->trace_fd, buf, recorder->page_size);