From patchwork Mon Nov 9 12:55:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 322722 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=-12.8 required=3.0 tests=BAYES_00,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 79AF0C388F7 for ; Mon, 9 Nov 2020 13:20:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C64D20731 for ; Mon, 9 Nov 2020 13:20:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928009; bh=c6strdFNX862Wnk98EAR6chwxrm6G0VD8w8sw8l1sco=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=SG6vDR00cnjs+YIHlOJX0OL7Q2gVrBAoNlibKvSmWZ/nY43NqUOy27kRo5Z1wvnhY s5arxnbbtf/0GjVY0QZ4GjPrG1bW2UwNMW2cOK77kQwtvou14eUW8qJHbKoxmUyJt3 7yw8Rx5EBKL/N/j/c0LTvvvPZYAZwhX/v6ymwo7k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387887AbgKINUI (ORCPT ); Mon, 9 Nov 2020 08:20:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:47602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387551AbgKINUF (ORCPT ); Mon, 9 Nov 2020 08:20:05 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 B62CE2076E; Mon, 9 Nov 2020 13:20:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928004; bh=c6strdFNX862Wnk98EAR6chwxrm6G0VD8w8sw8l1sco=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IA/NaK+H2X+sKsXojQwaN5fOkG12uqS8Q/90oyMchVIE0C0vXZb/AQ805qgsJqg7p Ffp1BHAAbfgNnuI3mEp3rRJbMsU3PjYKwSJAY2Bfl7/kvq53mhMs4X8kdhENZP9Heb PxF5BuC6nmCY/H6yt/jMIYGyIa1pvUVj3PoeuDIk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tyrel Datwyler , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 5.9 093/133] scsi: ibmvscsi: Fix potential race after loss of transport Date: Mon, 9 Nov 2020 13:55:55 +0100 Message-Id: <20201109125035.175407730@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125030.706496283@linuxfoundation.org> References: <20201109125030.706496283@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tyrel Datwyler [ Upstream commit 665e0224a3d76f36da40bd9012270fa629aa42ed ] After a loss of transport due to an adapter migration or crash/disconnect from the host partner there is a tiny window where we can race adjusting the request_limit of the adapter. The request limit is atomically increased/decreased to track the number of inflight requests against the allowed limit of our VIOS partner. After a transport loss we set the request_limit to zero to reflect this state. However, there is a window where the adapter may attempt to queue a command because the transport loss event hasn't been fully processed yet and request_limit is still greater than zero. The hypercall to send the event will fail and the error path will increment the request_limit as a result. If the adapter processes the transport event prior to this increment the request_limit becomes out of sync with the adapter state and can result in SCSI commands being submitted on the now reset connection prior to an SRP Login resulting in a protocol violation. Fix this race by protecting request_limit with the host lock when changing the value via atomic_set() to indicate no transport. Link: https://lore.kernel.org/r/20201025001355.4527-1-tyreld@linux.ibm.com Signed-off-by: Tyrel Datwyler Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/scsi/ibmvscsi/ibmvscsi.c | 36 +++++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 10 deletions(-) diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c index b1f3017b6547a..29fcc44be2d57 100644 --- a/drivers/scsi/ibmvscsi/ibmvscsi.c +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c @@ -806,6 +806,22 @@ static void purge_requests(struct ibmvscsi_host_data *hostdata, int error_code) spin_unlock_irqrestore(hostdata->host->host_lock, flags); } +/** + * ibmvscsi_set_request_limit - Set the adapter request_limit in response to + * an adapter failure, reset, or SRP Login. Done under host lock to prevent + * race with SCSI command submission. + * @hostdata: adapter to adjust + * @limit: new request limit + */ +static void ibmvscsi_set_request_limit(struct ibmvscsi_host_data *hostdata, int limit) +{ + unsigned long flags; + + spin_lock_irqsave(hostdata->host->host_lock, flags); + atomic_set(&hostdata->request_limit, limit); + spin_unlock_irqrestore(hostdata->host->host_lock, flags); +} + /** * ibmvscsi_reset_host - Reset the connection to the server * @hostdata: struct ibmvscsi_host_data to reset @@ -813,7 +829,7 @@ static void purge_requests(struct ibmvscsi_host_data *hostdata, int error_code) static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata) { scsi_block_requests(hostdata->host); - atomic_set(&hostdata->request_limit, 0); + ibmvscsi_set_request_limit(hostdata, 0); purge_requests(hostdata, DID_ERROR); hostdata->action = IBMVSCSI_HOST_ACTION_RESET; @@ -1146,13 +1162,13 @@ static void login_rsp(struct srp_event_struct *evt_struct) dev_info(hostdata->dev, "SRP_LOGIN_REJ reason %u\n", evt_struct->xfer_iu->srp.login_rej.reason); /* Login failed. */ - atomic_set(&hostdata->request_limit, -1); + ibmvscsi_set_request_limit(hostdata, -1); return; default: dev_err(hostdata->dev, "Invalid login response typecode 0x%02x!\n", evt_struct->xfer_iu->srp.login_rsp.opcode); /* Login failed. */ - atomic_set(&hostdata->request_limit, -1); + ibmvscsi_set_request_limit(hostdata, -1); return; } @@ -1163,7 +1179,7 @@ static void login_rsp(struct srp_event_struct *evt_struct) * This value is set rather than added to request_limit because * request_limit could have been set to -1 by this client. */ - atomic_set(&hostdata->request_limit, + ibmvscsi_set_request_limit(hostdata, be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta)); /* If we had any pending I/Os, kick them */ @@ -1195,13 +1211,13 @@ static int send_srp_login(struct ibmvscsi_host_data *hostdata) login->req_buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT | SRP_BUF_FORMAT_INDIRECT); - spin_lock_irqsave(hostdata->host->host_lock, flags); /* Start out with a request limit of 0, since this is negotiated in * the login request we are just sending and login requests always * get sent by the driver regardless of request_limit. */ - atomic_set(&hostdata->request_limit, 0); + ibmvscsi_set_request_limit(hostdata, 0); + spin_lock_irqsave(hostdata->host->host_lock, flags); rc = ibmvscsi_send_srp_event(evt_struct, hostdata, login_timeout * 2); spin_unlock_irqrestore(hostdata->host->host_lock, flags); dev_info(hostdata->dev, "sent SRP login\n"); @@ -1781,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq, return; case VIOSRP_CRQ_XPORT_EVENT: /* Hypervisor telling us the connection is closed */ scsi_block_requests(hostdata->host); - atomic_set(&hostdata->request_limit, 0); + ibmvscsi_set_request_limit(hostdata, 0); if (crq->format == 0x06) { /* We need to re-setup the interpartition connection */ dev_info(hostdata->dev, "Re-enabling adapter!\n"); @@ -2137,12 +2153,12 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata) } hostdata->action = IBMVSCSI_HOST_ACTION_NONE; + spin_unlock_irqrestore(hostdata->host->host_lock, flags); if (rc) { - atomic_set(&hostdata->request_limit, -1); + ibmvscsi_set_request_limit(hostdata, -1); dev_err(hostdata->dev, "error after %s\n", action); } - spin_unlock_irqrestore(hostdata->host->host_lock, flags); scsi_unblock_requests(hostdata->host); } @@ -2226,7 +2242,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id) init_waitqueue_head(&hostdata->work_wait_q); hostdata->host = host; hostdata->dev = dev; - atomic_set(&hostdata->request_limit, -1); + ibmvscsi_set_request_limit(hostdata, -1); hostdata->host->max_sectors = IBMVSCSI_MAX_SECTORS_DEFAULT; if (map_persist_bufs(hostdata)) {