Fix: hang in thread_rotation when using compat-poll

Add missing verification to prevent a blocking read on an empty fd.

Signed-off-by: Yannick Lamarre <ylamarre@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/rotation-thread.c b/src/bin/lttng-sessiond/rotation-thread.c
index 6669372dd471210470138dbab6605907fa15019d..b86b166892ad917fff5ba7f40366d0aa9bd08bc0 100644 (file)
--- a/src/bin/lttng-sessiond/rotation-thread.c
+++ b/src/bin/lttng-sessiond/rotation-thread.c
@@ -974,6 +974,10 @@ void *thread_rotation(void *data)
                        int fd = LTTNG_POLL_GETFD(&thread.events, i);
                        uint32_t revents = LTTNG_POLL_GETEV(&thread.events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
                        DBG("[rotation-thread] Handling fd (%i) activity (%u)",
                                        fd, revents);