BUG/MINOR: sink: make sure to always properly unmap a file-backed ring

The munmap() call performed on exit was incorrect since it used to apply
to the buffer instead of the area, so neither the pointer nor the size
were page-aligned. This patches corrects this and also adds a call to
msync() since munmap() alone doesn't guarantee that data will be dumped.

This should be backported to 2.6.

diff --git a/src/sink.c b/src/sink.c
index 862a1ae322837285ff8e028dd16cc7f91c828853..0aae5f2a7e74e91ad6405b653c261bf91b216053 100644 (file)
--- a/src/sink.c
+++ b/src/sink.c
@@ -1392,8 +1392,13 @@ static void sink_deinit()
 
        list_for_each_entry_safe(sink, sb, &sink_list, sink_list) {
                if (sink->type == SINK_TYPE_BUFFER) {
-                       if (sink->store)
-                               munmap(sink->ctx.ring->buf.area, sink->ctx.ring->buf.size);
+                       if (sink->store) {
+                               size_t size = (sink->ctx.ring->buf.size + 4095UL) & -4096UL;
+                               void *area = (sink->ctx.ring->buf.area - sizeof(*sink->ctx.ring));
+
+                               msync(area, size, MS_SYNC);
+                               munmap(area, size);
+                       }
                        else
                                ring_free(sink->ctx.ring);
                }