Fix: don't perform extra flush on metadata channel
[lttng-modules.git] / lib / ringbuffer / ring_buffer_vfs.c
index 33dfeaaaba4c5ce55df34ac97b9b812f78d8f565..71991ebb29554ba9b2df713a73750d6e79acc843 100644 (file)
@@ -28,6 +28,7 @@
 #include "../../wrapper/ringbuffer/frontend.h"
 #include "../../wrapper/ringbuffer/vfs.h"
 #include "../../wrapper/poll.h"
+#include "../../lttng-tracer.h"
 
 static int put_ulong(unsigned long val, unsigned long arg)
 {
@@ -41,6 +42,10 @@ static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
 }
 #endif
 
+/*
+ * This is not used by anonymous file descriptors. This code is left
+ * there if we ever want to implement an inode with open() operation.
+ */
 int lib_ring_buffer_open(struct inode *inode, struct file *file,
                struct lib_ring_buffer *buf)
 {
@@ -186,6 +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:
@@ -263,7 +277,7 @@ long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
                                 arg);
        }
        case RING_BUFFER_FLUSH:
-               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
+               lib_ring_buffer_switch_remote(buf);
                return 0;
        default:
                return -ENOIOCTLCMD;
@@ -315,6 +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:
@@ -408,7 +431,7 @@ long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
                return compat_put_ulong(read_offset, arg);
        }
        case RING_BUFFER_COMPAT_FLUSH:
-               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
+               lib_ring_buffer_switch_remote(buf);
                return 0;
        default:
                return -ENOIOCTLCMD;
@@ -444,3 +467,7 @@ EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers");
 MODULE_DESCRIPTION("Ring Buffer Library VFS");
+MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
+       __stringify(LTTNG_MODULES_MINOR_VERSION) "."
+       __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
+       LTTNG_MODULES_EXTRAVERSION);
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