Fix: perf counter context deadlock

[lttng-ust.git] / liblttng-ust / lttng-ust-statedump.c

diff --git a/liblttng-ust/lttng-ust-statedump.c b/liblttng-ust/lttng-ust-statedump.c
index c8e508cdf9e9bd477f333ce79046e42625d64922..644af303aa9ceae55bae10d899571d8999e02b26 100644 (file)
--- a/liblttng-ust/lttng-ust-statedump.c
+++ b/liblttng-ust/lttng-ust-statedump.c
@@ -431,13 +431,13 @@ void iter_end(struct dl_iterate_data *data, void *ip)
                                        trace_lib_load(&e->bin_data, ip);
                                        e->traced = true;
                                }
+                               e->marked = false;
                        } else {
                                if (e->traced)
                                        trace_lib_unload(&e->bin_data, ip);
                                remove_dl_node(e);
                                free_dl_node(e);
                        }
-                       e->marked = false;
                }
        }
        ust_unlock();
@@ -590,12 +590,22 @@ int do_baddr_statedump(void *owner)
  * session, statedumps from different processes may be
  * interleaved. The vpid context should be used to identify which
  * events belong to which process.
+ *
+ * Grab the ust_lock outside of the RCU read-side lock because we
+ * perform synchronize_rcu with the ust_lock held, which can trigger
+ * deadlocks otherwise.
  */
 int do_lttng_ust_statedump(void *owner)
 {
+       ust_lock_nocheck();
        trace_statedump_start(owner);
+       ust_unlock();
+
        do_baddr_statedump(owner);
+
+       ust_lock_nocheck();
        trace_statedump_end(owner);
+       ust_unlock();
 
        return 0;
 }