From: Mark Jamsek Subject: Re: fix deadlock in tog after Ctrl-C To: gameoftrees@openbsd.org Date: Mon, 24 Oct 2022 20:26:39 +1100 On 22-10-24 10:39AM, Stefan Sperling wrote: > Loading commits for a single file in a deep history can take a long time. > > Trying to abort commit loading with Ctrl-C can currently cause 'tog log' > to get stuck, waiting for got-read-pack to exit, while got-read-pack is > trying to send more commits to tog; See stack traces below. > This is a dead-lock situation and the user must resort to kill -9 > to resolve it. > > The patch below fixes this by closing the parent's side of the imsg > pipe before it waits for the child process to exit. Ctrl-C now results > in a brief "unexpected end of file" error from got-read-pack flashing up > before tog exists as expected. > > Ok? ok This works as described for me. And has incidentally reminded me of a related WIP branch I have locally that aims to enable user input while loading history. > diff /home/stsp/src/got > commit - bc854c7bc75429b27c69c3d76a040b8c428799ad > path + /home/stsp/src/got > blob - b23e07e8e54eaf89df334656dbd6aa25515290d2 > file + lib/pack.c > --- lib/pack.c > +++ lib/pack.c > @@ -791,7 +791,7 @@ pack_stop_privsep_child(struct got_pack *pack) > static const struct got_error * > pack_stop_privsep_child(struct got_pack *pack) > { > - const struct got_error *err = NULL; > + const struct got_error *err = NULL, *close_err = NULL; > > if (pack->privsep_child == NULL) > return NULL; > @@ -799,9 +799,12 @@ pack_stop_privsep_child(struct got_pack *pack) > err = got_privsep_send_stop(pack->privsep_child->imsg_fd); > if (err) > return err; > + if (close(pack->privsep_child->imsg_fd) == -1) > + close_err = got_error_from_errno("close"); > err = got_privsep_wait_for_child(pack->privsep_child->pid); > - if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL) > - err = got_error_from_errno("close"); > + if (close_err && err == NULL) > + err = close_err; > + imsg_clear(pack->privsep_child->ibuf); > free(pack->privsep_child->ibuf); > free(pack->privsep_child); > pack->privsep_child = NULL; > > > (gdb) bt > #0 _thread_sys_sendmsg () at /tmp/-:3 > #1 0x000006b6e7b2110e in _libc_sendmsg_cancel (s=3, msg=0x7f7ffffad530, flags=0) at /usr/src/lib/libc/sys/w_sendmsg.c:27 > #2 0x000006b71319e37e in msgbuf_write (msgbuf=0x7f7ffffbd8f0) at /usr/src/lib/libutil/imsg-buffer.c:277 > #3 0x000006b71319af62 in imsg_flush (ibuf=0x7f7ffffad8d0) at /usr/src/lib/libutil/imsg.c:290 > #4 0x000006b455d11417 in flush_imsg (ibuf=0x7f7ffffad8d0) at /home/stsp/src/got/libexec/got-read-pack/../../lib/privsep.c:198 > #5 0x000006b455d1139f in got_privsep_flush_imsg (ibuf=0x7f7ffffad8d0) at /home/stsp/src/got/libexec/got-read-pack/../../lib/privsep.c:209 > #6 0x000006b455d003f1 in send_traversed_commits (commit_ids=0x6b69a1c3000, ncommits=818, ibuf=0x7f7ffffad8d0) at /home/stsp/src/got/libexec/got-read-pack/got-read-pack.c:584 > #7 0x000006b455cfe80e in commit_traversal_request (imsg=0x7f7ffffad8b0, ibuf=0x7f7ffffad8d0, pack=0x6b6ad5856c0, packidx=0x6b6ad570080, objcache=0x7f7ffffad868) at /home/stsp/src/got/libexec/got-read-pack/got-read-pack.c:661 > #8 0x000006b455cfcb52 in main (argc=2, argv=0x7f7ffffbd988) at /home/stsp/src/got/libexec/got-read-pack/got-read-pack.c:2028 > (gdb) up > > > > (gdb) bt > #0 _thread_sys_wait4 () at /tmp/-:3 > #1 0x0000094b8b3e5a9e in _libc_wait4_cancel (wpid=81169, status=0x7f7ffffbfa68, options=0, rusage=0x94b8b40316a <_thread_sys_wait4+10>) at /usr/src/lib/libc/sys/w_wait4.c:27 > #2 0x00000948dc789b36 in got_privsep_wait_for_child (pid=81169) at /home/stsp/src/got/tog/../lib/privsep.c:91 > #3 0x00000948dc786bf8 in pack_stop_privsep_child (pack=0x94bcd99f968) at /home/stsp/src/got/tog/../lib/pack.c:802 > #4 0x00000948dc786a7a in got_pack_close (pack=0x94bcd99f968) at /home/stsp/src/got/tog/../lib/pack.c:816 > #5 0x00000948dc7991a0 in got_repo_close (repo=0x94bcd99f470) at /home/stsp/src/got/tog/../lib/repository.c:787 > #6 0x00000948dc75badb in stop_log_thread (s=0x94bcd9c7090) at /home/stsp/src/got/tog/tog.c:3036 > #7 0x00000948dc757468 in close_log_view (view=0x94bcd9c7000) at /home/stsp/src/got/tog/tog.c:3063 > #8 0x00000948dc75628b in view_close (view=0x94bcd9c7000) at /home/stsp/src/got/tog/tog.c:811 > #9 0x00000948dc755e8c in view_loop (view=0x94bcd9c7000) at /home/stsp/src/got/tog/tog.c:1840 > #10 0x00000948dc75338e in cmd_log (argc=1, argv=0x94aef14ee58) at /home/stsp/src/got/tog/tog.c:4050 > #11 0x00000948dc752bd1 in tog_log_with_path (argc=4, argv=0x7f7ffffbff10) at /home/stsp/src/got/tog/tog.c:9251 > #12 0x00000948dc752445 in main (argc=1, argv=0x7f7ffffbff10) at /home/stsp/src/got/tog/tog.c:9364 > (gdb) > -- Mark Jamsek GPG: F2FF 13DE 6A06 C471 CA80 E6E2 2930 DC66 86EE CF68