From 95e30b2a131ed1f94ab7a64326243943317aa18a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Wed, 22 Aug 2018 19:19:42 +0200 Subject: [PATCH] chardev: mark the calls that allow an implicit mux monitor MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This is mostly for readability of the code. Let's make it clear which callers can create an implicit monitor when the chardev is muxed. This will also enforce a safer behaviour, as we don't really support creating monitor anywhere/anytime at the moment. Add an assert() to make sure the programmer explicitely wanted that behaviour. There are documented cases, such as: -serial/-parallel/-virtioconsole and to less extent -debugcon. Less obvious and questionable ones are -gdb, SLIRP -guestfwd and Xen console. Add a FIXME note for those, but keep the support for now. Other qemu_chr_new() callers either have a fixed parameter/filename string or do not need it, such as -qtest: * qtest.c: qtest_init() Afaik, only used by tests/libqtest.c, without mux. I don't think we support it outside of qemu testing: drop support for implicit mux monitor (qemu_chr_new() call: no implicit mux now). * hw/ All with literal @filename argument that doesn't enable mux monitor. * tests/ All with @filename argument that doesn't enable mux monitor. On a related note, the list of monitor creation places: - the chardev creators listed above: all from command line (except perhaps Xen console?) - -gdb & hmp gdbserver will create a "GDB monitor command" chardev that is wired to an HMP monitor. - -mon command line option From this short study, I would like to think that a monitor may only be created in the main thread today, though I remain skeptical :) Signed-off-by: Marc-André Lureau Reviewed-by: Markus Armbruster --- chardev/char.c | 37 ++++++++++++++++++++++++++++++------- gdbstub.c | 6 +++++- hw/char/xen_console.c | 6 +++++- include/chardev/char.h | 24 ++++++++++++++++++++---- net/slirp.c | 6 +++++- vl.c | 10 +++++----- 6 files changed, 70 insertions(+), 19 deletions(-) diff --git a/chardev/char.c b/chardev/char.c index 76d866e6fe..e115166995 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -329,7 +329,8 @@ int qemu_chr_wait_connected(Chardev *chr, Error **errp) return 0; } -QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename) +QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename, + bool permit_mux_mon) { char host[65], port[33], width[8], height[8]; int pos; @@ -344,6 +345,10 @@ QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename) } if (strstart(filename, "mon:", &p)) { + if (!permit_mux_mon) { + error_report("mon: isn't supported in this context"); + return NULL; + } filename = p; qemu_opt_set(opts, "mux", "on", &error_abort); if (strcmp(filename, "stdio") == 0) { @@ -683,7 +688,8 @@ out: return chr; } -Chardev *qemu_chr_new_noreplay(const char *label, const char *filename) +Chardev *qemu_chr_new_noreplay(const char *label, const char *filename, + bool permit_mux_mon) { const char *p; Chardev *chr; @@ -694,25 +700,32 @@ Chardev *qemu_chr_new_noreplay(const char *label, const char *filename) return qemu_chr_find(p); } - opts = qemu_chr_parse_compat(label, filename); + opts = qemu_chr_parse_compat(label, filename, permit_mux_mon); if (!opts) return NULL; chr = qemu_chr_new_from_opts(opts, &err); - if (err) { + if (!chr) { error_report_err(err); + goto out; } - if (chr && qemu_opt_get_bool(opts, "mux", 0)) { + + if (qemu_opt_get_bool(opts, "mux", 0)) { + assert(permit_mux_mon); monitor_init(chr, MONITOR_USE_READLINE); } + +out: qemu_opts_del(opts); return chr; } -Chardev *qemu_chr_new(const char *label, const char *filename) +static Chardev *qemu_chr_new_permit_mux_mon(const char *label, + const char *filename, + bool permit_mux_mon) { Chardev *chr; - chr = qemu_chr_new_noreplay(label, filename); + chr = qemu_chr_new_noreplay(label, filename, permit_mux_mon); if (chr) { if (replay_mode != REPLAY_MODE_NONE) { qemu_chr_set_feature(chr, QEMU_CHAR_FEATURE_REPLAY); @@ -726,6 +739,16 @@ Chardev *qemu_chr_new(const char *label, const char *filename) return chr; } +Chardev *qemu_chr_new(const char *label, const char *filename) +{ + return qemu_chr_new_permit_mux_mon(label, filename, false); +} + +Chardev *qemu_chr_new_mux_mon(const char *label, const char *filename) +{ + return qemu_chr_new_permit_mux_mon(label, filename, true); +} + static int qmp_query_chardev_foreach(Object *obj, void *data) { Chardev *chr = CHARDEV(obj); diff --git a/gdbstub.c b/gdbstub.c index d6ab95006c..c8478de8f5 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -2038,7 +2038,11 @@ int gdbserver_start(const char *device) sigaction(SIGINT, &act, NULL); } #endif - chr = qemu_chr_new_noreplay("gdb", device); + /* + * FIXME: it's a bit weird to allow using a mux chardev here + * and implicitly setup a monitor. We may want to break this. + */ + chr = qemu_chr_new_noreplay("gdb", device, true); if (!chr) return -1; } diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c index 8b4b4bf523..44f7236382 100644 --- a/hw/char/xen_console.c +++ b/hw/char/xen_console.c @@ -207,7 +207,11 @@ static int con_init(struct XenDevice *xendev) } else { snprintf(label, sizeof(label), "xencons%d", con->xendev.dev); qemu_chr_fe_init(&con->chr, - qemu_chr_new(label, output), &error_abort); + /* + * FIXME: sure we want to support implicit + * muxed monitors here? + */ + qemu_chr_new_mux_mon(label, output), &error_abort); } xenstore_store_pv_console_info(con->xendev.dev, diff --git a/include/chardev/char.h b/include/chardev/char.h index 3e4fe6dad0..7becd8c80c 100644 --- a/include/chardev/char.h +++ b/include/chardev/char.h @@ -105,14 +105,27 @@ ChardevBackend *qemu_chr_parse_opts(QemuOpts *opts, * @filename: the URI * * Create a new character backend from a URI. + * Do not implicitly initialize a monitor if the chardev is muxed. * * Returns: a new character backend */ Chardev *qemu_chr_new(const char *label, const char *filename); /** - * qemu_chr_change: - * @opts: the new backend options + * qemu_chr_new_mux_mon: + * @label: the name of the backend + * @filename: the URI + * + * Create a new character backend from a URI. + * Implicitly initialize a monitor if the chardev is muxed. + * + * Returns: a new character backend + */ +Chardev *qemu_chr_new_mux_mon(const char *label, const char *filename); + +/** +* qemu_chr_change: +* @opts: the new backend options * * Change an existing character backend */ @@ -129,6 +142,7 @@ void qemu_chr_cleanup(void); * qemu_chr_new_noreplay: * @label: the name of the backend * @filename: the URI + * @permit_mux_mon: if chardev is muxed, initialize a monitor * * Create a new character backend from a URI. * Character device communications are not written @@ -136,7 +150,8 @@ void qemu_chr_cleanup(void); * * Returns: a new character backend */ -Chardev *qemu_chr_new_noreplay(const char *label, const char *filename); +Chardev *qemu_chr_new_noreplay(const char *label, const char *filename, + bool permit_mux_mon); /** * qemu_chr_be_can_write: @@ -194,7 +209,8 @@ bool qemu_chr_has_feature(Chardev *chr, ChardevFeature feature); void qemu_chr_set_feature(Chardev *chr, ChardevFeature feature); -QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename); +QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename, + bool permit_mux_mon); int qemu_chr_write(Chardev *s, const uint8_t *buf, int len, bool write_all); #define qemu_chr_write_all(s, buf, len) qemu_chr_write(s, buf, len, true) int qemu_chr_wait_connected(Chardev *chr, Error **errp); diff --git a/net/slirp.c b/net/slirp.c index c93b64dd91..99884de204 100644 --- a/net/slirp.c +++ b/net/slirp.c @@ -764,7 +764,11 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp) } } else { Error *err = NULL; - Chardev *chr = qemu_chr_new(buf, p); + /* + * FIXME: sure we want to support implicit + * muxed monitors here? + */ + Chardev *chr = qemu_chr_new_mux_mon(buf, p); if (!chr) { error_setg(errp, "Could not open guest forwarding device '%s'", diff --git a/vl.c b/vl.c index 0388852deb..a867c9c4d9 100644 --- a/vl.c +++ b/vl.c @@ -2310,7 +2310,7 @@ static void monitor_parse(const char *optarg, const char *mode, bool pretty) } else { snprintf(label, sizeof(label), "compat_monitor%d", monitor_device_index); - opts = qemu_chr_parse_compat(label, optarg); + opts = qemu_chr_parse_compat(label, optarg, true); if (!opts) { error_report("parse error: %s", optarg); exit(1); @@ -2382,7 +2382,7 @@ static int serial_parse(const char *devname) snprintf(label, sizeof(label), "serial%d", index); serial_hds = g_renew(Chardev *, serial_hds, index + 1); - serial_hds[index] = qemu_chr_new(label, devname); + serial_hds[index] = qemu_chr_new_mux_mon(label, devname); if (!serial_hds[index]) { error_report("could not connect serial device" " to character backend '%s'", devname); @@ -2418,7 +2418,7 @@ static int parallel_parse(const char *devname) exit(1); } snprintf(label, sizeof(label), "parallel%d", index); - parallel_hds[index] = qemu_chr_new(label, devname); + parallel_hds[index] = qemu_chr_new_mux_mon(label, devname); if (!parallel_hds[index]) { error_report("could not connect parallel device" " to character backend '%s'", devname); @@ -2449,7 +2449,7 @@ static int virtcon_parse(const char *devname) qemu_opt_set(dev_opts, "driver", "virtconsole", &error_abort); snprintf(label, sizeof(label), "virtcon%d", index); - virtcon_hds[index] = qemu_chr_new(label, devname); + virtcon_hds[index] = qemu_chr_new_mux_mon(label, devname); if (!virtcon_hds[index]) { error_report("could not connect virtio console" " to character backend '%s'", devname); @@ -2465,7 +2465,7 @@ static int debugcon_parse(const char *devname) { QemuOpts *opts; - if (!qemu_chr_new("debugcon", devname)) { + if (!qemu_chr_new_mux_mon("debugcon", devname)) { exit(1); } opts = qemu_opts_create(qemu_find_opts("device"), "debugcon", 1, NULL);