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Thu, 8 Mar 2018 01:01:43 -0500 Received: from mail-sn1nam01on0105.outbound.protection.outlook.com ([104.47.32.105]:54752 "EHLO NAM01-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965904AbeCHFC6 (ORCPT ); Thu, 8 Mar 2018 00:02:58 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Dean Jenkins , Marcel Holtmann , Sasha Levin Subject: [PATCH AUTOSEL for 4.9 124/190] Bluetooth: hci_ldisc: Add protocol check to hci_uart_tx_wakeup() Thread-Topic: [PATCH AUTOSEL for 4.9 124/190] Bluetooth: hci_ldisc: Add protocol check to hci_uart_tx_wakeup() Thread-Index: AQHTtppH81A3FcZObkS3K9pRFqOkSQ== Date: Thu, 8 Mar 2018 04:59:46 +0000 Message-ID: <20180308045810.8041-124-alexander.levin@microsoft.com> References: <20180308045810.8041-1-alexander.levin@microsoft.com> In-Reply-To: <20180308045810.8041-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1013;7:GcqqaIi8BC8xqyswy21zEYXj5Nx5sUQ7vr0a+ShCFOIUNB3m6U8bJ39AlIL6gxHc/04urYjnB36hpbn13fyAkgdgibhA6vx12BusNNF8P8fQ7Vu0rcpTpdefOOPtbRs69ZJpdYV3fWuZ1xnvgTZmTL2FPgYpILHIhmWCuhAWyG63RUFIV+MtjEmDSbMAOCKktX/l/VrbAVT1gsPz7quljuGD8ZrgUGN97n0D2wPGG4BlbbzDC9KcboQ4g4IOt6FU;20:M6dHHrazpl4ki+oXZvowwlBupSA8tFsFoRjRhxCX183MdL8l9+d+nwDXNagcesTYNbcN7HKQ9bro2hkrQfGX3Uvo/Thvwe+t5iBg+qDpV2pMyq5GNR7QAamURBDxfO1/YctcbIG346tuOrv40Yx88eHp5gfidoqmmSc7Vbvh7fg= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 1ac33d9f-8edd-445f-f165-08d584b1db38 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1013; 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x-microsoft-antispam-message-info: HXpCAQJx+BvIrjdb3d8eZveMFglvD9PwzdBn2ltjqqbI4dFdUtMvDArwwtOrvDhT35zP0MHzixcq/ULP+fxq17o/Dx89gN9AERzwHT+btpEL5tdUxlxTFQvitZyJeOIw3tsLJDAY8TqRIrSln3v+ZnWb0tKOFvo+eqvZyhcCofhUHAKMUL+pF9uvOCm1VW675K6rjBZ+lNyIs0kjR1sfMNdZs/bpJtH3wuf5CeIWpkl+qnMBsopLQX5D49RIccEfTTIbyBbiJ1/iwaliKswIPfihhQ50/4Qh7prYFDhfuK1D4iR95eJ3NuGjbf8vJ+88A+AjCVcZNF3zvakHTN2Mog== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1ac33d9f-8edd-445f-f165-08d584b1db38 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Mar 2018 04:59:46.3337 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1013 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Dean Jenkins [ Upstream commit 2d6f1da168e1d62c47f7d50135ac4cbd8411dcb1 ] Before attempting to schedule a work-item onto hu->write_work in hci_uart_tx_wakeup(), check that the Data Link protocol layer is still bound to the HCI UART driver. Failure to perform this protocol check causes a race condition between the work queue hu->write_work running hci_uart_write_work() and the Data Link protocol layer being unbound (closed) in hci_uart_tty_close(). Note hci_uart_tty_close() does have a "cancel_work_sync(&hu->write_work)" but it is ineffective because it cannot prevent work-items being added to hu->write_work after cancel_work_sync() has run. Therefore, add a check for HCI_UART_PROTO_READY into hci_uart_tx_wakeup() which prevents scheduling of the work queue when HCI_UART_PROTO_READY is in the clear state. However, note a small race condition remains because the hci_uart_tx_wakeup() thread can run in parallel with the hci_uart_tty_close() thread so it is possible that a schedule of hu->write_work can occur when HCI_UART_PROTO_READY is cleared. A complete solution needs locking of the threads which is implemented in a future commit. Signed-off-by: Dean Jenkins Signed-off-by: Marcel Holtmann Signed-off-by: Sasha Levin --- drivers/bluetooth/hci_ldisc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index 7ec73945351c..2230f9368c21 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -125,6 +125,9 @@ static inline struct sk_buff *hci_uart_dequeue(struct h= ci_uart *hu) =20 int hci_uart_tx_wakeup(struct hci_uart *hu) { + if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) + return 0; + if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) { set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); return 0; --=20 2.14.1