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,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 50865C18E5B for ; Tue, 10 Mar 2020 13:08:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21C3524691 for ; Tue, 10 Mar 2020 13:08:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583845732; bh=f+smNxhL2OfdgV7oDdGzlTppEvpqzeaeqjamekC+ckE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Dvkpp/FyLor+zxaaK4mFjCX0X5kbw+MRz86bqYqnKMSCwBnSduUEpviYQM17/OlzK 6iNU9L87mkshYvS6cmdi9BOStxHX8m3BvCJrYtr+JPd1oUbLslyCfsKIJHWub794ny 4ts0NF4COyRKBPZWloxBtxoUAAOjy1wGWeRWU/BA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730383AbgCJNIv (ORCPT ); Tue, 10 Mar 2020 09:08:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:55596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731155AbgCJNIr (ORCPT ); Tue, 10 Mar 2020 09:08:47 -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 9275824691; Tue, 10 Mar 2020 13:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583845727; bh=f+smNxhL2OfdgV7oDdGzlTppEvpqzeaeqjamekC+ckE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vJM/SnMsP4sHisPCc9WwMj0uuNFLpNu3HbhKTxJyJNL+MQsqpUFwVWTyp/uEb3QA8 PHBV97Wly+1JyXCGeeQrI//IOQi8EGhSNdYzRdrEMtyYH03HO8jKYR4VlgM1nnsfYT 8P+/4zINia6YVPoKUHoGTBEmkV2rUN1u18ZV3P7Q= 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 4.14 078/126] usb: gadget: serial: fix Tx stall after buffer overflow Date: Tue, 10 Mar 2020 13:41:39 +0100 Message-Id: <20200310124208.924610546@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310124203.704193207@linuxfoundation.org> References: <20200310124203.704193207@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 520ace49f91d9..942d2977797d7 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -715,8 +715,10 @@ 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