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[94.39.191.51]) by smtp.gmail.com with ESMTPSA id k75sm6042448wmh.10.2017.07.13.07.24.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jul 2017 07:24:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=93S9afDY3+DqAtyTbH+iQMCgh0ox0nsrlyiWNTR0q1o=; b=ucgHNrasSSILj3C7aEuusiC1ytujuwxCizpPD+0AcnkBldmI1t4j2+H9t09lshfXYB 5ButxrlGP8rxCrLoBn2xpNEDc7ejI5Nv8LkUJI5QiKpUOpI30KmueeWi7hBAspvcdCPJ IXzEMDxKN1Hu7UsDqo0QIyBOig5/cHKrHglnVXjBH5/sSvg78OS7+doxGU8h+c7HizwR TadgsgouN1Z0d6XZnsHCAB1spCiFV72jttBkIwpFjVUlYe0+bIcoqpsYUpEr2FOJsvsH aWYz0MB4KGuqQn+gsHrVEGn35cFsr7QukqMzmMCjgaaj+9oi7+4QhdcgcpC9JPz5E4kI 3c1Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=93S9afDY3+DqAtyTbH+iQMCgh0ox0nsrlyiWNTR0q1o=; b=TeUZi2z+/HAI7fEr9okJItTVmuVkq5kA871hhv0JYH/sN4Cz4OpuEdALB3R5BvcGlq iR7G7yJlyxyCuhr9UrYt0dbcm8pJxldYmRiwNMJHxapQ+lywY5C9/5uIrF+2XKJbSsl+ /fd3auQ1nnwHKnvaOU0cTxvsExI85j3fgihqzXYnIEL8u3knTy5ehHHMgALyZmu33k3X 1zNwUAIFDB1N0Jz0Mcnhuv4eD/93Jtzx9hbqiC8DSyWGrgGb18ot0NLrB08s5jEVRCsD pyRxSORfEiOtlLqcehgn6VWHv/iVDmBW1Sw7x094oYjDcT3Ehyapp+yNMK5qUhlbY14I KEYg== X-Gm-Message-State: AIVw112+zQ4YrulB2wyvbR2LDbj9/pwk801ZZFwbIV7aPh2Nlfp1NEn0 s/tsYCv45sL/xg8EJH8= X-Received: by 10.223.144.39 with SMTP id h36mr2093905wrh.114.1499955895807; Thu, 13 Jul 2017 07:24:55 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Thu, 13 Jul 2017 16:24:03 +0200 Message-Id: <1499955874-10954-11-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1499955874-10954-1-git-send-email-pbonzini@redhat.com> References: <1499955874-10954-1-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:400c:c0c::234 Subject: [Qemu-devel] [PULL 10/41] char: chardevice hotswap X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anton Nefedov Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 From: Anton Nefedov This patch adds a possibility to change a char device without a frontend removal. Ideally, it would have to happen transparently to a frontend, i.e. frontend would continue its regular operation. However, backends are not stateless and are set up by the frontends via qemu_chr_fe_<> functions, and it's not (generally) possible to replay that setup entirely in a backend code, as different chardevs respond to the setup calls differently, so do frontends work differently basing on those setup responses. Moreover, some frontend can generally get and save the backend pointer (qemu_chr_fe_get_driver()), and it will become invalid after backend change. So, a frontend which would like to support chardev hotswap has to register a "backend change" handler, and redo its backend setup there. Signed-off-by: Anton Nefedov Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <1499342940-56739-4-git-send-email-anton.nefedov@virtuozzo.com> Reviewed-by: Marc-Andr=C3=A9 Lureau Signed-off-by: Paolo Bonzini --- chardev/char.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++= ++++ include/chardev/char.h | 9 ++++++ qapi-schema.json | 40 ++++++++++++++++++++++++ 3 files changed, 132 insertions(+) diff --git a/chardev/char.c b/chardev/char.c index 839eff6..d6b9d89 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -951,6 +951,89 @@ ChardevReturn *qmp_chardev_add(const char *id, Chardev= Backend *backend, return ret; } =20 +ChardevReturn *qmp_chardev_change(const char *id, ChardevBackend *backend, + Error **errp) +{ + CharBackend *be; + const ChardevClass *cc; + Chardev *chr, *chr_new; + bool closed_sent =3D false; + ChardevReturn *ret; + + chr =3D qemu_chr_find(id); + if (!chr) { + error_setg(errp, "Chardev '%s' does not exist", id); + return NULL; + } + + if (CHARDEV_IS_MUX(chr)) { + error_setg(errp, "Mux device hotswap not supported yet"); + return NULL; + } + + if (qemu_chr_replay(chr)) { + error_setg(errp, + "Chardev '%s' cannot be changed in record/replay mode", id); + return NULL; + } + + be =3D chr->be; + if (!be) { + /* easy case */ + object_unparent(OBJECT(chr)); + return qmp_chardev_add(id, backend, errp); + } + + if (!be->chr_be_change) { + error_setg(errp, "Chardev user does not support chardev hotswap"); + return NULL; + } + + cc =3D char_get_class(ChardevBackendKind_lookup[backend->type], errp); + if (!cc) { + return NULL; + } + + chr_new =3D qemu_chardev_new(NULL, object_class_get_name(OBJECT_CLASS(= cc)), + backend, errp); + if (!chr_new) { + return NULL; + } + chr_new->label =3D g_strdup(id); + + if (chr->be_open && !chr_new->be_open) { + qemu_chr_be_event(chr, CHR_EVENT_CLOSED); + closed_sent =3D true; + } + + chr->be =3D NULL; + qemu_chr_fe_init(be, chr_new, &error_abort); + + if (be->chr_be_change(be->opaque) < 0) { + error_setg(errp, "Chardev '%s' change failed", chr_new->label); + chr_new->be =3D NULL; + qemu_chr_fe_init(be, chr, &error_abort); + if (closed_sent) { + qemu_chr_be_event(chr, CHR_EVENT_OPENED); + } + object_unref(OBJECT(chr_new)); + return NULL; + } + + object_unparent(OBJECT(chr)); + object_property_add_child(get_chardevs_root(), chr_new->label, + OBJECT(chr_new), &error_abort); + object_unref(OBJECT(chr_new)); + + ret =3D g_new0(ChardevReturn, 1); + if (CHARDEV_IS_PTY(chr_new)) { + ret->pty =3D g_strdup(chr_new->filename + 4); + ret->has_pty =3D true; + } + + return ret; +} + void qmp_chardev_remove(const char *id, Error **errp) { Chardev *chr; diff --git a/include/chardev/char.h b/include/chardev/char.h index 8a9ade4..22fd734 100644 --- a/include/chardev/char.h +++ b/include/chardev/char.h @@ -93,6 +93,15 @@ void qemu_chr_parse_common(QemuOpts *opts, ChardevCommon= *backend); Chardev *qemu_chr_new(const char *label, const char *filename); =20 /** + * @qemu_chr_change: + * + * Change an existing character backend + * + * @opts the new backend options + */ +void qemu_chr_change(QemuOpts *opts, Error **errp); + +/** * @qemu_chr_cleanup: * * Delete all chardevs (when leaving qemu) diff --git a/qapi-schema.json b/qapi-schema.json index 37c4b95..0090fbf 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -5098,6 +5098,46 @@ 'returns': 'ChardevReturn' } =20 ## +# @chardev-change: +# +# Change a character device backend +# +# @id: the chardev's ID, must exist +# @backend: new backend type and parameters +# +# Returns: ChardevReturn. +# +# Since: 2.10 +# +# Example: +# +# -> { "execute" : "chardev-change", +# "arguments" : { "id" : "baz", +# "backend" : { "type" : "pty", "data" : {} } } } +# <- { "return": { "pty" : "/dev/pty/42" } } +# +# -> {"execute" : "chardev-change", +# "arguments" : { +# "id" : "charchannel2", +# "backend" : { +# "type" : "socket", +# "data" : { +# "addr" : { +# "type" : "unix" , +# "data" : { +# "path" : "/tmp/charchannel2.socket" +# } +# }, +# "server" : true, +# "wait" : false }}}} +# <- {"return": {}} +# +## +{ 'command': 'chardev-change', 'data': {'id' : 'str', + 'backend' : 'ChardevBackend' }, + 'returns': 'ChardevReturn' } + +## # @chardev-remove: # # Remove a character device backend --=20 1.8.3.1