Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760673AbaLLGbo (ORCPT ); Fri, 12 Dec 2014 01:31:44 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51940 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759335AbaLLGQ6 (ORCPT ); Fri, 12 Dec 2014 01:16:58 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Paul Osmialowski" , "Matthew Dharm" , "Alan Stern" , "Greg Kroah-Hartman" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 111/164] usb-storage: handle a skipped data phase In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 93c9bf4d1838d5851a18ca398b0ad66397f05056 upstream. Sometimes mass-storage devices using the Bulk-only transport will mistakenly skip the data phase of a command. Rather than sending the data expected by the host or sending a zero-length packet, they go directly to the status phase and send the CSW. This causes problems for usb-storage, for obvious reasons. The driver will interpret the CSW as a short data transfer and will wait to receive a CSW. The device won't have anything left to send, so the command eventually times out. The SCSI layer doesn't retry commands after they time out (this is a relatively recent change). Therefore we should do our best to detect a skipped data phase and handle it promptly. This patch adds code to do that. If usb-storage receives a short 13-byte data transfer from the device, and if the first four bytes of the data match the CSW signature, the driver will set the residue to the full transfer length and interpret the data as a CSW. This fixes Bugzilla #86611. Signed-off-by: Alan Stern CC: Matthew Dharm Tested-by: Paul Osmialowski Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: use US_DEBUGP() not usb_stor_dbg()] Signed-off-by: Ben Hutchings --- drivers/usb/storage/transport.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) --- a/drivers/usb/storage/transport.c +++ b/drivers/usb/storage/transport.c @@ -1119,6 +1119,31 @@ int usb_stor_Bulk_transport(struct scsi_ */ if (result == USB_STOR_XFER_LONG) fake_sense = 1; + + /* + * Sometimes a device will mistakenly skip the data phase + * and go directly to the status phase without sending a + * zero-length packet. If we get a 13-byte response here, + * check whether it really is a CSW. + */ + if (result == USB_STOR_XFER_SHORT && + srb->sc_data_direction == DMA_FROM_DEVICE && + transfer_length - scsi_get_resid(srb) == + US_BULK_CS_WRAP_LEN) { + struct scatterlist *sg = NULL; + unsigned int offset = 0; + + if (usb_stor_access_xfer_buf((unsigned char *) bcs, + US_BULK_CS_WRAP_LEN, srb, &sg, + &offset, FROM_XFER_BUF) == + US_BULK_CS_WRAP_LEN && + bcs->Signature == + cpu_to_le32(US_BULK_CS_SIGN)) { + US_DEBUGP("Device skipped data phase\n"); + scsi_set_resid(srb, transfer_length); + goto skipped_data_phase; + } + } } /* See flow chart on pg 15 of the Bulk Only Transport spec for @@ -1154,6 +1179,7 @@ int usb_stor_Bulk_transport(struct scsi_ if (result != USB_STOR_XFER_GOOD) return USB_STOR_TRANSPORT_ERROR; + skipped_data_phase: /* check bulk status */ residue = le32_to_cpu(bcs->Residue); US_DEBUGP("Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n", -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/