From f27a9bb3e9c3bd822243f6fc1d921f1334e37acf Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 24 Feb 2020 15:30:05 +0100 Subject: [PATCH] qmp: Fail gracefully if chardev is already in use Trying to attach a QMP monitor to a chardev that is already in use results in a crash because monitor_init_qmp() passes &error_abort to qemu_chr_fe_init(): $ ./x86_64-softmmu/qemu-system-x86_64 --chardev stdio,id=foo --mon foo,mode=control --mon foo,mode=control Unexpected error in qemu_chr_fe_init() at chardev/char-fe.c:220: qemu-system-x86_64: --mon foo,mode=control: Device 'foo' is in use Abgebrochen (Speicherabzug geschrieben) Fix this by allowing monitor_init_qmp() to return an error and passing any error in qemu_chr_fe_init() to its caller instead of aborting. Signed-off-by: Kevin Wolf Message-Id: <20200224143008.13362-18-kwolf@redhat.com> Acked-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- include/monitor/monitor.h | 2 +- monitor/monitor.c | 7 ++++++- monitor/qmp.c | 11 +++++++---- stubs/monitor-core.c | 2 +- tests/test-util-sockets.c | 2 +- 5 files changed, 16 insertions(+), 8 deletions(-) diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h index db1112552c..e55a3b57e0 100644 --- a/include/monitor/monitor.h +++ b/include/monitor/monitor.h @@ -17,7 +17,7 @@ bool monitor_cur_is_qmp(void); void monitor_init_globals(void); void monitor_init_globals_core(void); -void monitor_init_qmp(Chardev *chr, bool pretty); +void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp); void monitor_init_hmp(Chardev *chr, bool use_readline); int monitor_init(MonitorOptions *opts, Error **errp); int monitor_init_opts(QemuOpts *opts, Error **errp); diff --git a/monitor/monitor.c b/monitor/monitor.c index f8a6ef795b..00d287655e 100644 --- a/monitor/monitor.c +++ b/monitor/monitor.c @@ -614,6 +614,7 @@ void monitor_init_globals_core(void) int monitor_init(MonitorOptions *opts, Error **errp) { Chardev *chr; + Error *local_err = NULL; chr = qemu_chr_find(opts->chardev); if (chr == NULL) { @@ -623,7 +624,7 @@ int monitor_init(MonitorOptions *opts, Error **errp) switch (opts->mode) { case MONITOR_MODE_CONTROL: - monitor_init_qmp(chr, opts->pretty); + monitor_init_qmp(chr, opts->pretty, &local_err); break; case MONITOR_MODE_READLINE: if (opts->pretty) { @@ -636,6 +637,10 @@ int monitor_init(MonitorOptions *opts, Error **errp) g_assert_not_reached(); } + if (local_err) { + error_propagate(errp, local_err); + return -1; + } return 0; } diff --git a/monitor/qmp.c b/monitor/qmp.c index 8379c8f96e..f89e7daf27 100644 --- a/monitor/qmp.c +++ b/monitor/qmp.c @@ -395,10 +395,16 @@ static void monitor_qmp_setup_handlers_bh(void *opaque) monitor_list_append(&mon->common); } -void monitor_init_qmp(Chardev *chr, bool pretty) +void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp) { MonitorQMP *mon = g_new0(MonitorQMP, 1); + if (!qemu_chr_fe_init(&mon->common.chr, chr, errp)) { + g_free(mon); + return; + } + qemu_chr_fe_set_echo(&mon->common.chr, true); + /* Note: we run QMP monitor in I/O thread when @chr supports that */ monitor_data_init(&mon->common, true, false, qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT)); @@ -408,9 +414,6 @@ void monitor_init_qmp(Chardev *chr, bool pretty) qemu_mutex_init(&mon->qmp_queue_lock); mon->qmp_requests = g_queue_new(); - qemu_chr_fe_init(&mon->common.chr, chr, &error_abort); - qemu_chr_fe_set_echo(&mon->common.chr, true); - json_message_parser_init(&mon->parser, handle_qmp_command, mon, NULL); if (mon->common.use_io_thread) { /* diff --git a/stubs/monitor-core.c b/stubs/monitor-core.c index 403c00a6d0..6cff1c4e1d 100644 --- a/stubs/monitor-core.c +++ b/stubs/monitor-core.c @@ -5,7 +5,7 @@ __thread Monitor *cur_mon; -void monitor_init_qmp(Chardev *chr, bool pretty) +void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp) { } diff --git a/tests/test-util-sockets.c b/tests/test-util-sockets.c index 8ce55efe70..2edb4c539d 100644 --- a/tests/test-util-sockets.c +++ b/tests/test-util-sockets.c @@ -71,7 +71,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) */ __thread Monitor *cur_mon; int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap) { abort(); } -void monitor_init_qmp(Chardev *chr, bool pretty) {} +void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp) {} void monitor_init_hmp(Chardev *chr, bool use_readline) {}