Fix: don't perform extra flush on metadata channel

[lttng-modules.git] / lib / ringbuffer / ring_buffer_vfs.c

diff --git a/lib/ringbuffer/ring_buffer_vfs.c b/lib/ringbuffer/ring_buffer_vfs.c
index f1a8bab781cd2f5829c552067eefdb2365c1f2e7..15da212d3fa313e3b3a027b2638132cacbb1db40 100644 (file)
--- a/lib/ringbuffer/ring_buffer_vfs.c
+++ b/lib/ringbuffer/ring_buffer_vfs.c
@@ -191,6 +191,15 @@ long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
 
        switch (cmd) {
        case RING_BUFFER_SNAPSHOT:
+               /*
+                * First, ensure we perform a "final" flush onto the
+                * stream.  This will ensure we create a packet of
+                * padding if we encounter an empty packet. This ensures
+                * the time-stamps right before the snapshot is used as
+                * end of packet timestamp.
+                */
+               if (!buf->quiescent)
+                       lib_ring_buffer_switch_remote_empty(buf);
                return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
                                            &buf->prod_snapshot);
        case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
@@ -320,6 +329,15 @@ long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 
        switch (cmd) {
        case RING_BUFFER_COMPAT_SNAPSHOT:
+               /*
+                * First, ensure we perform a "final" flush onto the
+                * stream.  This will ensure we create a packet of
+                * padding if we encounter an empty packet. This ensures
+                * the time-stamps right before the snapshot is used as
+                * end of packet timestamp.
+                */
+               if (!buf->quiescent)
+                       lib_ring_buffer_switch_remote_empty(buf);
                return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
                                                &buf->prod_snapshot);
        case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED: