From a08ac84b963facb4c4a85c4d5df057d44e2a276d Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Sun, 10 Jun 2018 15:21:31 +0200 Subject: [PATCH] [gdb/testsuite] Fix hang in fork-running-state.c When I run make check: ... $ cd build/gdb $ make check 2>&1 | tee ../CHECKLOG.gdb ... I see after ~30m the summary of the test run printed, but make still hangs. This seems to be due to some sleeping processes: ... $ ps fx | grep fork-run 6475 ? S 0:00 gdb.base/fork-running-state/fork-running-state 6451 ? S 0:00 gdb.base/fork-running-state/fork-running-state 6427 ? S 0:00 gdb.base/fork-running-state/fork-running-state ... Killing the sleeping processes like this: ... kill -9 $(ps -A | grep fork-running-st | awk '{print $1}') ... allows make to finish. If I isolate one debug session from fork-running-state.exp that causes one of these sleeping processes, we get: ... (gdb) set non-stop on (gdb) break main Breakpoint 1 at 0x400665: file src/gdb/testsuite/gdb.base/fork-running-state.c, line 52. (gdb) run Starting program: build/gdb/testsuite/outputs/gdb.base/fork-running-state/ fork-running-state Breakpoint 1, main () at src/gdb/testsuite/gdb.base/fork-running-state.c:52 52 save_parent = getpid (); (gdb) set detach-on-fork on (gdb) set follow-fork parent (gdb) continue & Continuing. [Detaching after fork from child process 18797] (gdb) info threads Id Target Id Frame * 1 process 18793 "fork-running-st" (running) (gdb) set print inferior-events off (gdb) kill inferior 1 ... So, AFAIU, the hanging process is the child process that gdb detaches from. There's an alarm set in main before the fork, but alarms are not preserved in the fork child: ... $ man alarm ... NOTES Alarms created by alarm() are preserved across execve(2) and are not inherited by children created via fork(2). ... So, AFAIU, once the parent is killed, there's no alarm to terminate the child. The patch fixes this by moving the setting of the alarm into the fork_main/fork_child functions, making sure that an alarm will trigger for the child. Tested with make check on x86_64. 2018-06-13 Tom de Vries PR testsuite/23269 * gdb.base/fork-running-state.c (main): Move setting of alarm ... (fork_child): ... here, and ... (fork_parent): ... here. --- gdb/testsuite/gdb.base/fork-running-state.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/gdb/testsuite/gdb.base/fork-running-state.c b/gdb/testsuite/gdb.base/fork-running-state.c index 8ea4739..65ca942 100644 --- a/gdb/testsuite/gdb.base/fork-running-state.c +++ b/gdb/testsuite/gdb.base/fork-running-state.c @@ -27,6 +27,9 @@ int save_parent; static int fork_child (void) { + /* Don't run forever. */ + alarm (180); + while (1) pause (); @@ -38,6 +41,9 @@ fork_child (void) static int fork_parent (void) { + /* Don't run forever. */ + alarm (180); + while (1) pause (); @@ -51,9 +57,6 @@ main (void) save_parent = getpid (); - /* Don't run forever. */ - alarm (180); - /* The parent and child should basically run forever without tripping on any debug event. We want to check that GDB updates the parent and child running states correctly right after the -- 2.7.4