From 8e4e0c7a49d8b216676f31f670f235308ff2117b Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 29 Sep 2021 15:53:52 +0200 Subject: [PATCH] Fix gdb.multi/multi-term-settings.exp race The gdb.multi/multi-term-settings.exp testcase sometimes fails like so: Running /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.multi/multi-term-settings.exp ... FAIL: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: stop with control-c (SIGINT) It's easier to reproduce if you stress the machine at the same time, like e.g.: $ stress -c 24 Looking at gdb.log, we see: (gdb) attach 60422 Attaching to program: build/gdb/testsuite/outputs/gdb.multi/multi-term-settings/multi-term-settings, process 60422 [New Thread 60422.60422] Reading symbols from /lib/x86_64-linux-gnu/libc.so.6... Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.31.so... Reading symbols from /lib64/ld-linux-x86-64.so.2... (No debugging symbols found in /lib64/ld-linux-x86-64.so.2) 0x00007f2fc2485334 in __GI___clock_nanosleep (clock_id=, clock_id@entry =0, flags=flags@entry =0, req=req@entry =0x7ffe23126940, rem=rem@entry =0x0) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:78 78 ../sysdeps/unix/sysv/linux/clock_nanosleep.c: No such file or directory. (gdb) PASS: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: inf2: attach set schedule-multiple on (gdb) PASS: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: set schedule-multiple on info inferiors Num Description Connection Executable 1 process 60404 1 (extended-remote localhost:2349) build/gdb/testsuite/outputs/gdb.multi/multi-term-settings/multi-term-settings * 2 process 60422 1 (extended-remote localhost:2349) build/gdb/testsuite/outputs/gdb.multi/multi-term-settings/multi-term-settings (gdb) PASS: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: info inferiors pid=60422, count=46 pid=60422, count=47 pid=60422, count=48 pid=60422, count=49 pid=60422, count=50 pid=60422, count=51 pid=60422, count=52 pid=60422, count=53 pid=60422, count=54 pid=60422, count=55 pid=60422, count=56 pid=60422, count=57 pid=60422, count=58 pid=60422, count=59 pid=60422, count=60 pid=60422, count=61 pid=60422, count=62 pid=60422, count=63 pid=60422, count=64 pid=60422, count=65 pid=60422, count=66 pid=60422, count=67 pid=60422, count=68 pid=60422, count=69 pid=60404, count=54 pid=60404, count=55 pid=60404, count=56 pid=60404, count=57 pid=60404, count=58 PASS: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: continue Quit (gdb) FAIL: gdb.multi/multi-term-settings.exp: inf1_how=attach: inf2_how=attach: stop with control-c (SIGINT) If you look at the testcase's sources, you'll see that the intention is to resumes the program with "continue", wait to see a few of those "pid=..., count=..." lines, and then interrupt the program with Ctrl-C. But somehow, that resulted in GDB printing "Quit", instead of the Ctrl-C stopping the program with SIGINT. Here's what is happening: #1 - those "pid=..., count=..." lines we see above weren't actually output by the inferior after it has been continued (see #1). Note that "inf1_how" and "inf2_how" are "attach". What happened is that those "pid=..., count=..." lines were output by the inferiors _before_ they were attached to. We see them at that point instead of earlier, because that's where the testcase reads from the inferiors' spawn_ids. #2 - The testcase mistakenly thinks those "pid=..., count=..." lines happened after the continue was processed by GDB, meaning it has waited enough, and so sends the Ctrl-C. GDB hasn't yet passed the terminal to the inferior, so the Ctrl-C results in that Quit. The fix here is twofold: #1 - flush inferior output right after attaching #2 - consume the "Continuing" printed by "continue", indicating the inferior has the terminal. This is the same as done throughout the testsuite to handle this exact problem of sending Ctrl-C too soon. gdb/testsuite/ChangeLog: yyyy-mm-dd Pedro Alves > * gdb.multi/multi-term-settings.exp (create_inferior): Flush inferior output. (coretest): Use $gdb_test_name. After issuing "continue", wait for "Continuing". Change-Id: Iba7671dfe1eee6b98d29cfdb05a1b9aa2f9defb9 --- .../gdb.multi/multi-term-settings.exp | 40 ++++++++++++++++--- 1 file changed, 34 insertions(+), 6 deletions(-) diff --git a/gdb/testsuite/gdb.multi/multi-term-settings.exp b/gdb/testsuite/gdb.multi/multi-term-settings.exp index 20ec03d94b3..dcc6f2ece0f 100644 --- a/gdb/testsuite/gdb.multi/multi-term-settings.exp +++ b/gdb/testsuite/gdb.multi/multi-term-settings.exp @@ -95,6 +95,22 @@ proc create_inferior {which_inf inf_how} { if {[gdb_test "attach $testpid" \ "Attaching to program: .*, process $testpid.*(in|at).*" \ "attach"] == 0} { + + # The program is now stopped, but if testing against + # gdbserver, then the inferior's output emmitted before it + # stopped isn't flushed unless we explicitly do so, + # because it is on a different spawn_id. Do it now, to + # avoid confusing tests further below. + gdb_test_multiple "" "flush inferior output" { + -timeout 1 + -i $test_spawn_id -re "pid=" { + exp_continue + } + timeout { + pass $gdb_test_name + } + } + return $test_spawn_id } } else { @@ -179,9 +195,9 @@ proc coretest {inf1_how inf2_how} { uplevel 1 { if {$count1 >= 3 && $count2 >= 3} { if $expect_ttou { - fail "$test (expected SIGTTOU)" + fail "$gdb_test_name (expected SIGTTOU)" } else { - pass $test + pass $gdb_test_name } } else { exp_continue @@ -195,8 +211,20 @@ proc coretest {inf1_how inf2_how} { set count1 0 set count2 0 - set test "continue" - gdb_test_multiple $test $test { + # We're going to interrupt with Ctrl-C. For this to work we must + # be sure to consume the "Continuing." message first, or GDB may + # still own the terminal. Also, note that in the attach case, we + # flushed inferior output right after attaching, so that we're + # sure that the "pid=" lines we see are emitted by the inferior + # after it is continued, instead of having been emitted before it + # was attached to. + gdb_test_multiple "continue" "continue, hand over terminal" { + -re "Continuing" { + pass $gdb_test_name + } + } + + gdb_test_multiple "" "continue" { -i $infs_spawn_ids -re "pid=$pid1, count=" { incr count1 pass_or_exp_continue @@ -207,9 +235,9 @@ proc coretest {inf1_how inf2_how} { } -i $gdb_spawn_id -re "received signal SIGTTOU.*$gdb_prompt " { if $expect_ttou { - pass "$test (expected SIGTTOU)" + pass "$gdb_test_name (expected SIGTTOU)" } else { - fail "$test (SIGTTOU)" + fail "$gdb_test_name (SIGTTOU)" } } } -- 2.30.2