From patchwork Thu Apr 15 08:16:18 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 50228 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id F2B28B7CF3 for ; Thu, 15 Apr 2010 18:35:08 +1000 (EST) Received: from localhost ([127.0.0.1]:33052 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O2KQQ-0007GN-Fy for incoming@patchwork.ozlabs.org; Thu, 15 Apr 2010 04:27:50 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O2KHI-0005SU-0e for qemu-devel@nongnu.org; Thu, 15 Apr 2010 04:18:24 -0400 Received: from [140.186.70.92] (port=34962 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O2KHG-0005RV-JN for qemu-devel@nongnu.org; Thu, 15 Apr 2010 04:18:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O2KH9-0001CE-T8 for qemu-devel@nongnu.org; Thu, 15 Apr 2010 04:18:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44793) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O2KH9-0001C1-LZ for qemu-devel@nongnu.org; Thu, 15 Apr 2010 04:18:15 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o3F8I6rO006481 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 15 Apr 2010 04:18:06 -0400 Received: from localhost (vpn-237-59.phx2.redhat.com [10.3.237.59]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o3F8I4fp000499; Thu, 15 Apr 2010 04:18:05 -0400 From: Amit Shah To: qemu list Date: Thu, 15 Apr 2010 13:46:18 +0530 Message-Id: <1271319378-9811-5-git-send-email-amit.shah@redhat.com> In-Reply-To: <1271319378-9811-4-git-send-email-amit.shah@redhat.com> References: <1271319378-9811-1-git-send-email-amit.shah@redhat.com> <1271319378-9811-2-git-send-email-amit.shah@redhat.com> <1271319378-9811-3-git-send-email-amit.shah@redhat.com> <1271319378-9811-4-git-send-email-amit.shah@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: Amit Shah , Gerd Hoffmann , paul@codesourcery.com Subject: [Qemu-devel] [PATCH v3 4/4] virtio-console: Throttle virtio-serial-bus if we can't consume any more guest data X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org If the char device we're connected to is overwhelmed with data and it can't accept any more, signal to the virtio-serial-bus to stop sending us more data till we tell otherwise. If the current buffer being processed hasn't been completely written out to the char device, we have to keep it around and re-try sending it since the virtio-serial-bus code assumes we consume the entire buffer. Allow the chardev backends to return -EAGAIN; we're ready with a callback handler that will flush the remainder of the buffer. Also register with savevm so that we save/restore such a buffer across migration. Signed-off-by: Amit Shah --- hw/virtio-console.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 123 insertions(+), 4 deletions(-) diff --git a/hw/virtio-console.c b/hw/virtio-console.c index 1552f47..1f8e695 100644 --- a/hw/virtio-console.c +++ b/hw/virtio-console.c @@ -13,18 +13,92 @@ #include "qemu-char.h" #include "virtio-serial.h" +typedef struct Buffer { + uint8_t *buf; + size_t rem_len; + size_t offset; +} Buffer; + typedef struct VirtConsole { VirtIOSerialPort port; CharDriverState *chr; + Buffer *unflushed_buf; } VirtConsole; +static void add_unflushed_buf(VirtConsole *vcon, const uint8_t *buf, size_t len) +{ + vcon->unflushed_buf = qemu_malloc(sizeof(Buffer)); + vcon->unflushed_buf->buf = qemu_malloc(len); + + memcpy(vcon->unflushed_buf->buf, buf, len); + vcon->unflushed_buf->rem_len = len; + vcon->unflushed_buf->offset = 0; +} + +static void free_unflushed_buf(VirtConsole *vcon) +{ + if (vcon->unflushed_buf) { + qemu_free(vcon->unflushed_buf->buf); + qemu_free(vcon->unflushed_buf); + vcon->unflushed_buf = NULL; + } +} + +static int buffered_write_to_chardev(VirtConsole *vcon, const uint8_t *buf, + size_t len) +{ + size_t written; + ssize_t ret; + + written = 0; + do { + ret = qemu_chr_write(vcon->chr, buf + written, len - written); + if (ret < 0) { + if (vcon->unflushed_buf) { + vcon->unflushed_buf->offset += written; + vcon->unflushed_buf->rem_len -= written; + } else { + virtio_serial_throttle_port(&vcon->port, true); + add_unflushed_buf(vcon, buf + written, len - written); + } + + return -EAGAIN; + } + + written += ret; + } while (written != len); + + return 0; +} + +/* Callback function called when the chardev can accept more data */ +static void chr_write_unblocked(void *opaque) +{ + VirtConsole *vcon = opaque; + + if (vcon->unflushed_buf) { + int ret; + + ret = buffered_write_to_chardev(vcon, vcon->unflushed_buf->buf + + vcon->unflushed_buf->offset, + vcon->unflushed_buf->rem_len); + if (ret < 0) { + return; + } + free_unflushed_buf(vcon); + } + virtio_serial_throttle_port(&vcon->port, false); +} /* Callback function that's called when the guest sends us data */ static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) { VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); - qemu_chr_write(vcon->chr, buf, len); + /* If a previous write was incomplete, we should've been throttled. */ + assert(!vcon->unflushed_buf); + + buffered_write_to_chardev(vcon, buf, len); } /* Readiness of the guest to accept data on a port */ @@ -48,25 +122,69 @@ static void chr_event(void *opaque, int event) VirtConsole *vcon = opaque; switch (event) { - case CHR_EVENT_OPENED: { + case CHR_EVENT_OPENED: virtio_serial_open(&vcon->port); break; - } + case CHR_EVENT_CLOSED: + if (vcon->unflushed_buf) { + free_unflushed_buf(vcon); + } virtio_serial_close(&vcon->port); break; } } +static void virtio_console_port_save(QEMUFile *f, void *opaque) +{ + VirtConsole *vcon = opaque; + uint32_t have_buffer; + + have_buffer = vcon->unflushed_buf ? true : false; + + qemu_put_be32s(f, &have_buffer); + if (have_buffer) { + qemu_put_be64s(f, &vcon->unflushed_buf->rem_len); + qemu_put_buffer(f, vcon->unflushed_buf->buf + + vcon->unflushed_buf->offset, + vcon->unflushed_buf->rem_len); + } +} + +static int virtio_console_port_load(QEMUFile *f, void *opaque, int version_id) +{ + VirtConsole *vcon = opaque; + uint32_t have_buffer; + + if (version_id > 1) { + return -EINVAL; + } + + qemu_get_be32s(f, &have_buffer); + if (have_buffer) { + vcon->unflushed_buf = qemu_mallocz(sizeof(Buffer)); + + qemu_get_be64s(f, &vcon->unflushed_buf->rem_len); + vcon->unflushed_buf->buf = qemu_malloc(vcon->unflushed_buf->rem_len); + vcon->unflushed_buf->offset = 0; + + qemu_get_buffer(f, vcon->unflushed_buf->buf, + vcon->unflushed_buf->rem_len); + } + return 0; +} + static int generic_port_init(VirtConsole *vcon, VirtIOSerialDevice *dev) { vcon->port.info = dev->info; if (vcon->chr) { qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, - NULL, chr_event, vcon); + chr_write_unblocked, chr_event, vcon); vcon->port.info->have_data = flush_buf; } + register_savevm("virtio-console-ports", -1, 1, virtio_console_port_save, + virtio_console_port_load, vcon); return 0; } @@ -88,6 +206,7 @@ static int virtconsole_exitfn(VirtIOSerialDevice *dev) if (vcon->chr) { port->info->have_data = NULL; qemu_chr_close(vcon->chr); + free_unflushed_buf(vcon); } return 0;