binutils-gdb/gdb/testsuite/gdb.threads
Tom de Vries b73715df01 [gdb] Handle vfork in thread with follow-fork-mode child
When debugging any of the testcases added by this commit, which do a
vfork in a thread with "set follow-fork-mode child" + "set
detach-on-fork on", we run into this assertion:

...
src/gdb/nat/x86-linux-dregs.c:146: internal-error: \
  void x86_linux_update_debug_registers(lwp_info*): \
  Assertion `lwp_is_stopped (lwp)' failed.
...

The assert is caused by the following: the vfork-child exit or exec
event is handled by handle_vfork_child_exec_or_exit, which calls
target_detach to detach from the vfork parent.  During target_detach
we call linux_nat_target::detach, which:

#1 - stops all the threads
#2 - waits for all the threads to be stopped
#3 - detaches all the threads

However, during the second step we run into this code in
stop_wait_callback:

...
  /* If this is a vfork parent, bail out, it is not going to report
     any SIGSTOP until the vfork is done with.  */
  if (inf->vfork_child != NULL)
    return 0;
...

and we don't wait for the threads to be stopped, which results in this
assert in x86_linux_update_debug_registers triggering during the third
step:

...
  gdb_assert (lwp_is_stopped (lwp));
...

The fix is to reset the vfork parent's vfork_child field before
calling target_detach in handle_vfork_child_exec_or_exit.  There's
already similar code for the other paths handled by
handle_vfork_child_exec_or_exit, so this commit refactors the code a
bit so that all paths share the same code.

The new tests cover both a vfork child exiting, and a vfork child
execing, since both cases would trigger the assertion.

The new testcases also exercise following the vfork children with "set
detach-on-fork off", since it doesn't seem to be tested anywhere.

Tested on x86_64-linux, using native and native-gdbserver.

gdb/ChangeLog:
2019-04-18  Tom de Vries  <tdevries@suse.de>
	    Pedro Alves  <palves@redhat.com>

	PR gdb/24454
	* infrun.c (handle_vfork_child_exec_or_exit): Reset vfork parent's
	vfork_child field before calling target_detach.

gdb/testsuite/ChangeLog:
2019-04-18  Tom de Vries  <tdevries@suse.de>
	    Pedro Alves  <palves@redhat.com>

	PR gdb/24454
	* gdb.threads/vfork-follow-child-exec.c: New file.
	* gdb.threads/vfork-follow-child-exec.exp: New file.
	* gdb.threads/vfork-follow-child-exit.c: New file.
	* gdb.threads/vfork-follow-child-exit.exp: New file.
2019-04-18 17:05:43 +01:00
..
attach-into-signal.c
attach-into-signal.exp
attach-many-short-lived-threads.c
attach-many-short-lived-threads.exp
attach-slow-waitpid.c
attach-slow-waitpid.exp
attach-stopped.c
attach-stopped.exp
bp_in_thread.c
bp_in_thread.exp
break-while-running.c
break-while-running.exp
check-libthread-db.c
check-libthread-db.exp
clone-attach-detach.c
clone-attach-detach.exp
clone-new-thread-event.c
clone-new-thread-event.exp
clone-thread_db.c
clone-thread_db.exp
continue-pending-after-query.c
continue-pending-after-query.exp
continue-pending-status.c
continue-pending-status.exp
corethreads.c
corethreads.exp
create-fail.c
create-fail.exp
current-lwp-dead.c
current-lwp-dead.exp
dlopen-libpthread-lib.c
dlopen-libpthread.c
dlopen-libpthread.exp
execl1.c
execl.c
execl.exp
fork-child-threads.c
fork-child-threads.exp
fork-plus-threads.c
fork-plus-threads.exp
fork-thread-pending.c
fork-thread-pending.exp
forking-threads-plus-breakpoint.c
forking-threads-plus-breakpoint.exp
gcore-stale-thread.c
gcore-stale-thread.exp
gcore-thread.exp
hand-call-in-threads.c
hand-call-in-threads.exp
hand-call-new-thread.c
hand-call-new-thread.exp
ia64-sigill.c
ia64-sigill.exp
info-threads-cur-sal-2.c
info-threads-cur-sal.c
info-threads-cur-sal.exp
interrupt-while-step-over.c
interrupt-while-step-over.exp
interrupted-hand-call.c
interrupted-hand-call.exp
kill.c
kill.exp
killed.c
killed.exp
leader-exit.c
leader-exit.exp
linux-dp.c
linux-dp.exp
local-watch-wrong-thread.c
local-watch-wrong-thread.exp
manythreads.c
manythreads.exp
multi-create-ns-info-thr.exp
multi-create.c
multi-create.exp
multiple-step-overs.c
multiple-step-overs.exp
multiple-successive-infcall.c
multiple-successive-infcall.exp
names.c
names.exp
next-bp-other-thread.c
next-bp-other-thread.exp
next-while-other-thread-longjmps.c
next-while-other-thread-longjmps.exp
no-unwaited-for-left.c
no-unwaited-for-left.exp
non-ldr-exc-1.c
non-ldr-exc-1.exp
non-ldr-exc-2.c
non-ldr-exc-2.exp
non-ldr-exc-3.c
non-ldr-exc-3.exp
non-ldr-exc-4.c
non-ldr-exc-4.exp
non-ldr-exit.c
non-ldr-exit.exp
non-stop-fair-events.c
non-stop-fair-events.exp
pending-step.c
pending-step.exp
print-threads.c
print-threads.exp
process-dies-while-detaching.c
process-dies-while-detaching.exp
process-dies-while-handling-bp.c
process-dies-while-handling-bp.exp
pthread_cond_wait.c
pthread_cond_wait.exp
pthreads.c
pthreads.exp
queue-signal.c
queue-signal.exp
reconnect-signal.c
reconnect-signal.exp
schedlock.c
schedlock.exp
siginfo-threads.c
siginfo-threads.exp
signal-command-handle-nopass.c
signal-command-handle-nopass.exp
signal-command-multiple-signals-pending.c
signal-command-multiple-signals-pending.exp
signal-delivered-right-thread.c
signal-delivered-right-thread.exp
signal-sigtrap.c
signal-sigtrap.exp
signal-while-stepping-over-bp-other-thread.c
signal-while-stepping-over-bp-other-thread.exp
sigstep-threads.c
sigstep-threads.exp
sigthread.c
sigthread.exp
slow-waitpid.c
staticthreads.c
staticthreads.exp
step-bg-decr-pc-switch-thread.c
step-bg-decr-pc-switch-thread.exp
step-over-lands-on-breakpoint.c
step-over-lands-on-breakpoint.exp
step-over-trips-on-watchpoint.c
step-over-trips-on-watchpoint.exp
stepi-random-signal.c
stepi-random-signal.exp
switch-threads.c
switch-threads.exp
thread_check.c
thread_check.exp
thread_events.c
thread_events.exp
thread-execl.c
thread-execl.exp
thread-find.exp
thread-specific-bp.c
thread-specific-bp.exp
thread-specific.c
thread-specific.exp
thread-unwindonsignal.exp
threadapply.c
threadapply.exp
threxit-hop-specific.c
threxit-hop-specific.exp
tid-reuse.c
tid-reuse.exp
tls2.c
tls-core.c
tls-core.exp
tls-main.c
tls-nodebug-pie.c
tls-nodebug-pie.exp
tls-nodebug.c
tls-nodebug.exp
tls-shared.c
tls-shared.exp
tls-so_extern_main.c
tls-so_extern.c
tls-so_extern.exp
tls-var-main.c
tls-var.c
tls-var.exp
tls.c
tls.exp
vfork-follow-child-exec.c
vfork-follow-child-exec.exp
vfork-follow-child-exit.c
vfork-follow-child-exit.exp
watchpoint-fork-child.c
watchpoint-fork-mt.c
watchpoint-fork-parent.c
watchpoint-fork-st.c
watchpoint-fork.exp
watchpoint-fork.h
watchthreads2.c
watchthreads2.exp
watchthreads-reorder.c
watchthreads-reorder.exp
watchthreads.c
watchthreads.exp
wp-replication.c
wp-replication.exp