Fix: baddr deadlock with lttng-ust destructor

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

diff --git a/liblttng-ust/lttng-ust-baddr.c b/liblttng-ust/lttng-ust-baddr.c
index 1e6e08dc6343627a2a261dca4619798b7993915b..681ba543bcd0ad6ab417b6a04e11c983021a95b1 100644 (file)
--- a/liblttng-ust/lttng-ust-baddr.c
+++ b/liblttng-ust/lttng-ust-baddr.c
@@ -29,23 +29,27 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <stdio.h>
-#include "usterr.h"
 
+#include <usterr-signal-safe.h>
+#include "lttng-tracer-core.h"
 #include "lttng-ust-baddr.h"
 
 #define TRACEPOINT_DEFINE
 #include "ust_baddr_statedump.h"
 
-static int
-extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
+static
+int extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
 {
        int j;
        int num_loadable_segment = 0;
+       void *owner = data;
+       struct cds_list_head *sessionsp;
 
        for (j = 0; j < info->dlpi_phnum; j++) {
                char resolved_path[PATH_MAX];
                struct stat sostat;
                void *base_addr_ptr;
+               struct lttng_session *session;
 
                if (info->dlpi_phdr[j].p_type != PT_LOAD)
                        continue;
@@ -83,10 +87,30 @@ extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
                        sostat.st_mtime = -1;
                }
 
-               tracepoint(ust_baddr_statedump, soinfo,
-                               (struct lttng_session *) data, base_addr_ptr,
-                               resolved_path, sostat.st_size, sostat.st_mtime);
+               /*
+                * UST lock needs to be nested within dynamic loader
+                * lock.
+                */
+               if (ust_lock()) {
+                       /*
+                        * Stop iteration on headers if need to exit.
+                        */
+                       ust_unlock();
+                       return 1;
+               }
 
+               sessionsp = _lttng_get_sessions();
+               cds_list_for_each_entry(session, sessionsp, node) {
+                       if (session->owner != owner)
+                               continue;
+                       if (!session->statedump_pending)
+                               continue;
+                       tracepoint(ust_baddr_statedump, soinfo,
+                                       session, base_addr_ptr,
+                                       resolved_path, sostat.st_size,
+                                       sostat.st_mtime);
+               }
+               ust_unlock();
                /*
                 * We are only interested in the base address (lowest virtual
                 * address associated with the memory image), skip the rest
@@ -96,15 +120,15 @@ extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
        return 0;
 }
 
-int
-lttng_ust_baddr_statedump(struct lttng_session *session)
+int lttng_ust_baddr_statedump(void *owner)
 {
        if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP"))
                return 0;
        /*
         * Iterate through the list of currently loaded shared objects and
-        * generate events for loadable segments using extract_soinfo_events
+        * generate events for loadable segments using
+        * extract_soinfo_events.
         */
-       dl_iterate_phdr(extract_soinfo_events, session);
+       dl_iterate_phdr(extract_soinfo_events, owner);
        return 0;
 }