From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60674C10F27 for ; Tue, 10 Mar 2020 12:42:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 247612469E for ; Tue, 10 Mar 2020 12:42:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583844140; bh=3tsSw4jgessdiPGEVOtj2pNmUIlDeuL0uPmLRPFww7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=s8+C0WUrAkNpcQkZa1S+G41ycB8B7K15usTrLZvRvJcMhzqKpB60tXfO32Q5LLpcO dHtWnOGL7E6k+qwwIolWgKpyz630qLSdDzsSlU0GoMoN6pmqSX4YCkj3Xpi5bPfOjV 6gUr8C9W8GKRCx9CVNXRDJzUp1SANCROCzkU1jUU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727307AbgCJMmT (ORCPT ); Tue, 10 Mar 2020 08:42:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:42120 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727286AbgCJMmP (ORCPT ); Tue, 10 Mar 2020 08:42:15 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 72AAA246A1; Tue, 10 Mar 2020 12:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583844134; bh=3tsSw4jgessdiPGEVOtj2pNmUIlDeuL0uPmLRPFww7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rb79BpEd/wPbldgMUinSakA5Hpn33xo2exOf/mRviUJY3BRZMMexn+SZns7lBfU9K 874nHmI8uZfUgpjfWsEviJoHmqDlvaSrvh+CUPMOBR3JG9CHbcuLVbIl0WizHpVsZa 4uT6J6U+ejdMZNv60obvDAnD4WriS2JMizNsCBq4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Organov , =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= , Felipe Balbi , Sasha Levin Subject: [PATCH 4.4 42/72] usb: gadget: serial: fix Tx stall after buffer overflow Date: Tue, 10 Mar 2020 13:38:55 +0100 Message-Id: <20200310123611.870381032@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310123601.053680753@linuxfoundation.org> References: <20200310123601.053680753@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sergey Organov [ Upstream commit e4bfded56cf39b8d02733c1e6ef546b97961e18a ] Symptom: application opens /dev/ttyGS0 and starts sending (writing) to it while either USB cable is not connected, or nobody listens on the other side of the cable. If driver circular buffer overflows before connection is established, no data will be written to the USB layer until/unless /dev/ttyGS0 is closed and re-opened again by the application (the latter besides having no means of being notified about the event of establishing of the connection.) Fix: on open and/or connect, kick Tx to flush circular buffer data to USB layer. Signed-off-by: Sergey Organov Reviewed-by: Michał Mirosław Signed-off-by: Felipe Balbi Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_serial.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 31e08bb3cb41e..58a699cfa4582 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -701,8 +701,10 @@ static int gs_start_io(struct gs_port *port) port->n_read = 0; started = gs_start_rx(port); - /* unblock any pending writes into our circular buffer */ if (started) { + gs_start_tx(port); + /* Unblock any pending writes into our circular buffer, in case + * we didn't in gs_start_tx() */ tty_wakeup(port->port.tty); } else { gs_free_requests(ep, head, &port->read_allocated); -- 2.20.1