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chardev: mark the calls that allow an implicit mux monitor

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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 <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Marc-André Lureau 2018-08-22 19:19:42 +02:00
parent 5662576ad0
commit 95e30b2a13
6 changed files with 70 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
chardev/char.c
View File

@ -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);

6
gdbstub.c
View File

@ -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;
}

6
hw/char/xen_console.c
View File

@ -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,

24
include/chardev/char.h
View File

@ -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);

6
net/slirp.c
View File

@ -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'",

10
vl.c
View File

@ -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);