Fix: allow get/put subbuf in loop for metadata stream

[lttng-modules.git] / lttng-events.c

diff --git a/lttng-events.c b/lttng-events.c
index 27a8f8644477be0bcf41c3732622e0e8c0f9fa57..567df65acea12345f51e46c937efa5f95cb15202 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -561,8 +561,16 @@ int lttng_metadata_output_channel(struct lttng_channel *chan,
        int ret = 0;
        size_t len, reserve_len;
 
+       /*
+        * Ensure we support mutiple get_next / put sequences followed
+        * by put_next.
+        */
+       WARN_ON(stream->metadata_in < stream->metadata_out);
+       if (stream->metadata_in != stream->metadata_out)
+               return 0;
+
        len = stream->metadata_cache->metadata_written -
-               stream->metadata_cache_read;
+               stream->metadata_in;
        if (!len)
                return 0;
        reserve_len = min_t(size_t,
@@ -579,10 +587,10 @@ int lttng_metadata_output_channel(struct lttng_channel *chan,
                goto end;
        }
        chan->ops->event_write(&ctx,
-                       stream->metadata_cache->data + stream->metadata_cache_read,
+                       stream->metadata_cache->data + stream->metadata_in,
                        reserve_len);
        chan->ops->event_commit(&ctx);
-       stream->metadata_cache_read += reserve_len;
+       stream->metadata_in += reserve_len;
        ret = reserve_len;
 
 end: