s3/lib: add option "serverid watch:debug = yes" to print kernel stack of hanging...

We only do if sys_have_proc_fds() returns true, so it's most likely
linux...

Enabled by default with log level 10...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15624

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Ralph Boehme <slow@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>
(cherry picked from commit 5c57e840527432c4b1a7ec94894939022a9e9622)

diff --git a/source3/lib/server_id_watch.c b/source3/lib/server_id_watch.c
index 50b35f27b3e29a04ec7ecf656424ed9de1bc96cb..c372ec8c43176c763be572f38a75882c304e3d9b 100644 (file)
--- a/source3/lib/server_id_watch.c
+++ b/source3/lib/server_id_watch.c
@@ -17,17 +17,18 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "replace.h"
-#include <tevent.h>
-#include <talloc.h>
+#include "includes.h"
 #include "serverid.h"
 #include "server_id_watch.h"
+#include "lib/util/server_id.h"
 #include "lib/util/tevent_unix.h"
 
 struct server_id_watch_state {
        struct tevent_context *ev;
        struct server_id pid;
        struct timeval start;
+       struct timeval warn;
+       bool debug;
 };
 
 static void server_id_watch_waited(struct tevent_req *subreq);
@@ -47,6 +48,12 @@ struct tevent_req *server_id_watch_send(TALLOC_CTX *mem_ctx,
        state->ev = ev;
        state->pid = pid;
        state->start = tevent_timeval_current();
+       state->warn = tevent_timeval_add(&state->start, 10, 0);
+
+       state->debug = lp_parm_bool(GLOBAL_SECTION_SNUM,
+                                   "serverid watch",
+                                   "debug",
+                                   CHECK_DEBUGLVL(DBGLVL_DEBUG));
 
        if (!serverid_exists(&state->pid)) {
                tevent_req_done(req);
@@ -86,6 +93,55 @@ static void server_id_watch_waited(struct tevent_req *subreq)
        }
 
        now = tevent_timeval_current();
+
+       if (!state->debug) {
+               goto next;
+       }
+
+       if (timeval_compare(&state->warn, &now) == -1) {
+               double duration = timeval_elapsed2(&state->start, &now);
+               char proc_path[64] = { 0, };
+               char *kstack = NULL;
+               struct server_id_buf buf;
+               const char *pid = server_id_str_buf(state->pid, &buf);
+               int ret;
+
+               state->warn = tevent_timeval_add(&now, 10, 0);
+
+               if (!procid_is_local(&state->pid) || !sys_have_proc_fds()) {
+                       DBG_ERR("Process %s hanging for %f seconds?\n",
+                               pid, duration);
+                       goto next;
+               }
+
+               ret = snprintf(proc_path,
+                              ARRAY_SIZE(proc_path),
+                              "/proc/%" PRIu64 "/stack",
+                              state->pid.pid);
+               if (ret < 0) {
+                       DBG_ERR("Process %s hanging for %f seconds?\n"
+                               "snprintf failed\n",
+                               pid, duration);
+                       goto next;
+               }
+
+               become_root();
+               kstack = file_load(proc_path, NULL, 0, state);
+               unbecome_root();
+               if (kstack == NULL) {
+                       DBG_ERR("Process %s hanging for %f seconds?\n"
+                               "file_load [%s] failed\n",
+                               pid, duration, proc_path);
+                       goto next;
+               }
+
+               DBG_ERR("Process %s hanging for %f seconds?\n"
+                       "%s:\n%s",
+                       pid, duration, proc_path, kstack);
+               TALLOC_FREE(kstack);
+       }
+
+next:
        next = tevent_timeval_add(&now, 0, 500000);
        subreq = tevent_wakeup_send(state, state->ev, next);
        if (tevent_req_nomem(subreq, req)) {