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Re: [Qemu-devel] [PATCH v2] chardev: add hotplug support.


From: Lei Li
Subject: Re: [Qemu-devel] [PATCH v2] chardev: add hotplug support.
Date: Mon, 15 Oct 2012 14:51:10 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0

On 10/12/2012 08:39 PM, Gerd Hoffmann wrote:
This patch adds chardev_add and chardev_del monitor commands.

chardev_del is pretty straight forward, it just takes an id argument and
zaps the chardev specified.

chardev_add is more tricky as there are tons of arguments for the
different backends.  The hmp version limited to the most common use
cases, especially when it comes to sockets:  You can only specify port
(tcp) or path (unix) and qemu will create a listening socket.  For
example this ...

    (qemu) chardev_add foo socket 42

... will do the same as ...

    -chardev socket,id=foo,port=42,server,nowait

on the qemu command line.

The qmp version has full support for everything the -chardev command
line switch can handle.  The implementation is pretty straight
forward: It just puts all arguments it got into a QemuOpts, then goes
call qemu_chr_new_from_opts().

Signed-off-by: Gerd Hoffmann <address@hidden>
---
  hmp-commands.hx  |   32 ++++++++++++++++++++++++++++
  hmp.c            |   31 +++++++++++++++++++++++++++
  hmp.h            |    2 +
  qapi-schema.json |   39 ++++++++++++++++++++++++++++++++++
  qemu-char.c      |   50 +++++++++++++++++++++++++++++++++++++++++++-
  qemu-char.h      |    2 +
  qmp-commands.hx  |   61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
  7 files changed, 216 insertions(+), 1 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index e0b537d..48504d1 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1404,6 +1404,38 @@ passed since 1970, i.e. unix epoch.
  ETEXI

      {
+        .name       = "chardev_add",
+        .args_type  = "args:s",
+        .params     = "args",
+        .help       = "add chardev",
+        .mhandler.cmd = hmp_chardev_add,
+    },
+
+STEXI
address@hidden chardev_add args
address@hidden chardev_add
+
+chardev_add accepts the same parameters as the -chardev command line switch.
+
+ETEXI
+
+    {
+        .name       = "chardev_del",
+        .args_type  = "id:s",
+        .params     = "id",
+        .help       = "del chardev",
+        .mhandler.cmd = hmp_chardev_del,
+    },
+
+STEXI
address@hidden chardev_del id
address@hidden chardev_del
+
+Removes the chardev @var{id}.
+
+ETEXI
+
+    {
          .name       = "info",
          .args_type  = "item:s?",
          .params     = "[subcommand]",
diff --git a/hmp.c b/hmp.c
index 70bdec2..b494d05 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1209,3 +1209,34 @@ void hmp_screen_dump(Monitor *mon, const QDict *qdict)
      qmp_screendump(filename, &err);
      hmp_handle_error(mon, &err);
  }
+
+void hmp_chardev_add(Monitor *mon, const QDict *qdict)
+{
+    const char *args = qdict_get_str(qdict, "args");
+    CharDriverState *chr;
+    Error *err = NULL;
+    QemuOpts *opts;
+
+    opts = qemu_opts_parse(qemu_find_opts("chardev"), args, 1);
+    if (opts == NULL) {
+        error_setg(&err, "Parsing chardev args failed\n");
+        goto out;
+    }
+
+    chr = qemu_chr_new_from_opts(opts, NULL);
+    if (chr == NULL) {
+        qemu_opts_del(opts);
+        error_setg(&err, "Creating chardev failed\n");
+    }
+
+out:
+    hmp_handle_error(mon, &err);
+}
+
+void hmp_chardev_del(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+    qmp_chardev_del(qdict_get_str(qdict, "id"),
+                    &err);
+    hmp_handle_error(mon, &err);
+}
diff --git a/hmp.h b/hmp.h
index 71ea384..080afaa 100644
--- a/hmp.h
+++ b/hmp.h
@@ -75,5 +75,7 @@ void hmp_getfd(Monitor *mon, const QDict *qdict);
  void hmp_closefd(Monitor *mon, const QDict *qdict);
  void hmp_send_key(Monitor *mon, const QDict *qdict);
  void hmp_screen_dump(Monitor *mon, const QDict *qdict);
+void hmp_chardev_add(Monitor *mon, const QDict *qdict);
+void hmp_chardev_del(Monitor *mon, const QDict *qdict);

  #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index f9dbdae..550e4c7 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2796,3 +2796,42 @@
  # Since: 0.14.0
  ##
  { 'command': 'screendump', 'data': {'filename': 'str'} }
+
+##
+# @chardev_add:
+#
+# Add a chardev
+#
+# @id: the chardev's ID, must be unique
+# @backend: the chardev backend: "file", "socket", ...
+# @path: file / device / unix socket path
+# @name: spice channel name
+# @host: host name
+# @port: port number
+# @server: create socket in server mode
+# @wait: wait for connect
+# @ipv4: force ipv4-only
+# @ipv6: force ipv6-only
+# @telnet: telnet negotiation
+#
+# Returns: Nothing on success
+#
+# Since: 1.3.0
+##
+{ 'command': 'chardev_add', 'data': {'id'      : 'str',
+                                     'backend' : 'str',
+                                     '*props'  : '**' },
+  'gen': 'no' }
+
+##
+# @chardev_del:
+#
+# Remove a chardev
+#
+# @id: the chardev's ID, must exist and not be in use
+#
+# Returns: Nothing on success
+#
+# Since: 1.3.0
+##
+{ 'command': 'chardev_del', 'data': {'id': 'str'} }
diff --git a/qemu-char.c b/qemu-char.c
index b082bae..7bbc490 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2805,6 +2805,7 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
          chr->avail_connections = 1;
      }
      chr->label = g_strdup(qemu_opts_id(opts));
+    chr->opts = opts;
      return chr;
  }

@@ -2826,7 +2827,6 @@ CharDriverState *qemu_chr_new(const char *label, const 
char *filename, void (*in
      if (chr && qemu_opt_get_bool(opts, "mux", 0)) {
          monitor_init(chr, MONITOR_USE_READLINE);
      }
-    qemu_opts_del(opts);
      return chr;
  }

@@ -2856,6 +2856,7 @@ void qemu_chr_delete(CharDriverState *chr)
      QTAILQ_REMOVE(&chardevs, chr, next);
      if (chr->chr_close)
          chr->chr_close(chr);
+    qemu_opts_del(chr->opts);
      g_free(chr->filename);
      g_free(chr->label);
      g_free(chr);
@@ -2900,3 +2901,50 @@ CharDriverState *qemu_char_get_next_serial(void)
      return serial_hds[next_serial++];
  }

+int qmp_chardev_add(Monitor *mon, const QDict *qdict, QObject **ret)
+{
+    CharDriverState *chr;
+    Error *err = NULL;
+    QemuOptsList *opts_list;
+    QemuOpts *opts;
+
+    opts_list = qemu_find_opts_err("chardev", &err);
+    if (error_is_set(&err)) {
+        goto exit_err;
+    }
+
+    opts = qemu_opts_from_qdict(opts_list, qdict, &err);
+    if (error_is_set(&err)) {
+        goto exit_err;
+    }
+
+    chr = qemu_chr_new_from_opts(opts, NULL);
+    if (chr == NULL) {
+        qemu_opts_del(opts);
+        error_setg(&err, "Creating chardev failed\n");
+        goto exit_err;
+    }
+    return 0;
+
+exit_err:
+    qerror_report_err(err);
+    error_free(err);
+    return -1;
+}
+
+void qmp_chardev_del(const char *id, Error **errp)
+{
+    CharDriverState *chr;
+
+    chr = qemu_chr_find(id);
+    if (NULL == chr) {
+        error_setg(errp, "Chardev '%s' not found\n", id);

Maybe this should be replaced by QERR_ macros to keep
compatibility since this one is listed in ErrorClass
in the schema, like:

error_set(errp, QERR_DEVICE_NOT_FOUND, id);

+        return;
+    }
+    if (chr->chr_can_read || chr->chr_read ||
+        chr->chr_event || chr->handler_opaque) {
+        error_setg(errp, "Chardev '%s' is busy\n", id);
+        return;
+    }
+    qemu_chr_delete(chr);
+}
diff --git a/qemu-char.h b/qemu-char.h
index 486644b..a910a60 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -74,6 +74,7 @@ struct CharDriverState {
      char *filename;
      int opened;
      int avail_connections;
+    QemuOpts *opts;
      QTAILQ_ENTRY(CharDriverState) next;
  };

@@ -236,6 +237,7 @@ void qemu_chr_info(Monitor *mon, QObject **ret_data);
  CharDriverState *qemu_chr_find(const char *name);

  QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
+int qmp_chardev_add(Monitor *mon, const QDict *qdict, QObject **ret);

  /* add an eventfd to the qemu devices that are polled */
  CharDriverState *qemu_chr_open_eventfd(int eventfd);
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 2f8477e..ebc1cee 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -2576,3 +2576,64 @@ EQMP
          .args_type  = "",
          .mhandler.cmd_new = qmp_marshal_input_query_target,
      },
+
+    {
+        .name       = "chardev_add",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_chardev_add,
+    },
+
+SQMP
+chardev_add
+-----------
+
+Add a chardev.
+
+Arguments:
+
+- "id": the chardev's ID, must be unique (json-string)
+- "backend": the chardev backend: "file", "socket", ... (json-string)
+- "path": file / device / unix socket path (json-string, optional)
+- "name": spice channel name (json-string, optional)
+- "host": host name (json-string, optional)
+- "port": port number (json-string, optional)
+- "server": create socket in server mode (json-bool, optional)
+- "wait": wait for connect (json-bool, optional)
+- "ipv4": force ipv4-only (json-bool, optional)
+- "ipv6": force ipv6-only (json-bool, optional)
+- "telnet": telnet negotiation (json-bool, optional)
+

Should it support the option "mux" to enable multiplexing mode?

+Example:
+
+-> { "execute": "chardev_add", "arguments": { "id"      : "foo",
+                                              "backend" : "socket",
+                                              "path"    : "/tmp/foo",
+                                              "server"  : "on",
+                                              "wait"    : "off" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "chardev_del",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_chardev_del,
+    },
+
+
+SQMP
+chardev_del
+-----------
+
+Remove a chardev.
+
+Arguments:
+
+- "id": the chardev's ID, must exist and not be in use (json-string)
+
+Example:
+
+-> { "execute": "chardev_del", "arguments": { "id" : "foo" } }
+<- { "return": {} }
+
+EQMP


--
Lei




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