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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 6D498C3F2CD for ; Tue, 3 Mar 2020 02:51:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33723246D9 for ; Tue, 3 Mar 2020 02:51:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583203889; bh=3tsSw4jgessdiPGEVOtj2pNmUIlDeuL0uPmLRPFww7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=H4fJ8EyshPxmP1ipOE5OLSfsfh3d74UmZLVQAMt/9B2aZ1Ex4JuaOkqji4VPDNEfB sbZq7w1N3YsMhlwHM9AelAHauE3bLbShuA/WByimGdUVcKqYsxF5hn8R3/d+YwPCW7 cKdoTPj0oAKf9hfKnVFdlRVbAnP5dN4lctG6HvJ8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728619AbgCCCv2 (ORCPT ); Mon, 2 Mar 2020 21:51:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:47274 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729163AbgCCCu0 (ORCPT ); Mon, 2 Mar 2020 21:50:26 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A215D246EC; Tue, 3 Mar 2020 02:50:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583203825; bh=3tsSw4jgessdiPGEVOtj2pNmUIlDeuL0uPmLRPFww7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nBQGH9vTt5tmKdOBZEoQFl0ExdeqFhWVMO3JhElUXYnY1mYUWJ1x4ha+M/TzlMUrC nt9eocOvN6nyyG05fqB5xHq5uBenuHYJ5ZR6O63eMhWJSrt/jSqi2bTOrBr83DFqlC SuBN8jVOHKX6flJHwT6oTbPfeiUoo4sT5hpn+GE4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sergey Organov , =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= , Felipe Balbi , Sasha Levin , linux-usb@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 03/11] usb: gadget: serial: fix Tx stall after buffer overflow Date: Mon, 2 Mar 2020 21:50:13 -0500 Message-Id: <20200303025021.10754-3-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200303025021.10754-1-sashal@kernel.org> References: <20200303025021.10754-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@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