From FEDORA_PATCHES Mon Sep 17 00:00:00 2001

From: Kevin Buettner <kevinb@redhat.com>

Date: Fri, 19 Mar 2021 11:07:11 -0700

Subject: gdb-rhbz1941080-fix-gdbserver-hang.patch

;; Backport change which fixes gdbserver testing hang on f34 and rawhide.

Fix potential hang during gdbserver testing

We're currently seeing testing of native-extended-gdbserver hang while

testing the x86_64 architecture on both Fedora 34 and Fedora Rawhide.

The test responsible for the hang is gdb.threads/fork-plus-threads.exp.

While there is clearly a problem/bug with this test on F34 and

Rawhide, it's also the case that testing should not hang.  This commit

prevents the hang by waiting with the "-nowait" flag in

close_gdbserver.

The -nowait flag is also used in the kill_wait_spawned_process proc in

gdb/testsuite/lib/gdb.exp, so there is precedent for doing this.

There are also 15 other uses of "wait -i" scattered throughout the

test suite.  While it's tempting to change these to also use the

-nowait flag, I think it might be safer to defer doing so until we

actually see a problem.

I've tested this patch on Fedora 32, 33, 34, and Rawhide.  Results are

comparable on Fedora 32 and 33.  On Fedora 34 and Rawhide, with this

commit in place, testing completes when the target_board is

native-extended-gdbserver.  On those OSes, when not using this commit,

testing usually hangs due to a problem with

gdb.threads/fork-plus-threads.exp.  I've also tested on all of the

mentioned OSes with target_board=native-gdbserver; for that testing,

I achieved comparable results over a number of runs.  (Unfortunately

results are rarely identical due to racy tests.)

gdb/testsuite/ChangeLog:

	* lib/gdbserver-support.exp (gdbserver_exit): Use the

	"-nowait" flag when waiting for gdbserver to exit.

diff --git a/gdb/testsuite/lib/gdbserver-support.exp b/gdb/testsuite/lib/gdbserver-support.exp

--- a/gdb/testsuite/lib/gdbserver-support.exp

+++ b/gdb/testsuite/lib/gdbserver-support.exp

@@ -418,7 +418,12 @@ proc close_gdbserver {} {

     verbose "Quitting GDBserver"

     catch "close -i $server_spawn_id"

-    catch "wait -i $server_spawn_id"

+

+    # If gdbserver misbehaves, and ignores the close, waiting for it

+    # without the -nowait flag will cause testing to hang.  Passing

+    # -nowait makes expect tell Tcl to wait for the process in the

+    # background.

+    catch "wait -nowait -i $server_spawn_id"

     unset server_spawn_id

 }