From patchwork Mon Oct 18 13:57:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Bogdanov X-Patchwork-Id: 12566567 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D560C433F5 for ; Mon, 18 Oct 2021 14:00:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 814A86058D for ; Mon, 18 Oct 2021 14:00:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234757AbhJROCt (ORCPT ); Mon, 18 Oct 2021 10:02:49 -0400 Received: from mta-02.yadro.com ([89.207.88.252]:48816 "EHLO mta-01.yadro.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234588AbhJROAj (ORCPT ); Mon, 18 Oct 2021 10:00:39 -0400 Received: from localhost (unknown [127.0.0.1]) by mta-01.yadro.com (Postfix) with ESMTP id 3591241253; Mon, 18 Oct 2021 13:58:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=yadro.com; h= content-type:content-type:content-transfer-encoding:mime-version :x-mailer:message-id:date:date:subject:subject:from:from :received:received:received; s=mta-01; t=1634565502; x= 1636379903; bh=aA6Ft8tDrOPQEeGGun4ebXEd66+dGl6I0OCBvKRX0RA=; b=O Wkb7JR9tqvZT4TXfRW+gGc9q+uFLZrvpxgXinIXXQS3Xec6FTZfj8cKawVez84Zv 6wwBntY0D6alj7EYNvuw0HtnGY1A4n5vpsMgmV4mgCYxzVDkfi7NmbzeWai5lsSm e76z9DlZAkqdGU4VyKY+mVLxKxpOcjfukAEfgLNkMg= X-Virus-Scanned: amavisd-new at yadro.com Received: from mta-01.yadro.com ([127.0.0.1]) by localhost (mta-01.yadro.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HxTxLK8gE6gy; Mon, 18 Oct 2021 16:58:22 +0300 (MSK) Received: from T-EXCH-04.corp.yadro.com (t-exch-04.corp.yadro.com [172.17.100.104]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mta-01.yadro.com (Postfix) with ESMTPS id 843864120B; Mon, 18 Oct 2021 16:58:22 +0300 (MSK) Received: from NB-591.corp.yadro.com (10.178.112.183) by T-EXCH-04.corp.yadro.com (172.17.100.104) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.1.669.32; Mon, 18 Oct 2021 16:58:21 +0300 From: Dmitry Bogdanov To: Martin Petersen , CC: Mike Christie , , , Dmitry Bogdanov , Roman Bolshakov Subject: [PATCH v4] target: core: remove from tmr_list at lun unlink Date: Mon, 18 Oct 2021 16:57:53 +0300 Message-ID: <20211018135753.15297-1-d.bogdanov@yadro.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.178.112.183] X-ClientProxiedBy: T-EXCH-01.corp.yadro.com (172.17.10.101) To T-EXCH-04.corp.yadro.com (172.17.100.104) Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Currently TMF commands are removed from de_device.dev_tmf_list at the very end of se_cmd lifecycle. But se_lun unlinks from se_cmd up on a command status (response) is queued in transport layer. It means that LUN and backend device can be deleted meantime and at the moment of repsonse completion a panic is occured: target_tmr_work() cmd->se_tfo->queue_tm_rsp(cmd); // send abort_rsp to a wire transport_lun_remove_cmd(cmd) // unlink se_cmd from se_lun - // - // - // - <<<--- lun remove <<<--- core backend device remove - // - // - // - qlt_handle_abts_completion() tfo->free_mcmd() transport_generic_free_cmd() target_put_sess_cmd() core_tmr_release_req() { if (dev) { // backend device, can not be null spin_lock_irqsave(&dev->se_tmr_lock, flags); //<<<--- CRASH Call Trace: NIP [c000000000e1683c] _raw_spin_lock_irqsave+0x2c/0xc0 LR [c00800000e433338] core_tmr_release_req+0x40/0xa0 [target_core_mod] Call Trace: (unreliable) 0x0 target_put_sess_cmd+0x2a0/0x370 [target_core_mod] transport_generic_free_cmd+0x6c/0x1b0 [target_core_mod] tcm_qla2xxx_complete_mcmd+0x28/0x50 [tcm_qla2xxx] process_one_work+0x2c4/0x5c0 worker_thread+0x88/0x690 For FC protocol it is a race condition, but for iSCSI protocol it is easyly reproduced by manual sending iSCSI commands: - Send some SCSI sommand - Send Abort of that command over iSCSI - Remove LUN on target - Send next iSCSI command to acknowledge the Abort_Response - target panics There is no sense to keep the command in tmr_list until response completion, so move the removal from tmr_list from the response completion to the response queueing when lun is unlinked. Move the removal from state list too as it is a subject to the same race condition. Fixes: c66ac9db8d4a ("[SCSI] target: Add LIO target core v4.0.0-rc6") Reviewed-by: Roman Bolshakov Signed-off-by: Dmitry Bogdanov Reviewed-by: Mike Christie --- v4: remove superfluous transport_lookup_tmr_lun that could race with lun reset v3: remove iscsi fix as not related to the issue avoid double removal from tmr_list v2: fix stuck in tmr list in error case The issue exists from the very begining. I uploaded a scapy script that helps to reproduce the issue at https://gist.github.com/logost/cb93df41dd2432454324449b390403c4 --- drivers/target/target_core_tmr.c | 17 +-------------- drivers/target/target_core_transport.c | 30 ++++++++++++++++++++------ 2 files changed, 24 insertions(+), 23 deletions(-) diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index e7fcbc09f9db..bac111456fa1 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -50,15 +50,6 @@ EXPORT_SYMBOL(core_tmr_alloc_req); void core_tmr_release_req(struct se_tmr_req *tmr) { - struct se_device *dev = tmr->tmr_dev; - unsigned long flags; - - if (dev) { - spin_lock_irqsave(&dev->se_tmr_lock, flags); - list_del_init(&tmr->tmr_list); - spin_unlock_irqrestore(&dev->se_tmr_lock, flags); - } - kfree(tmr); } @@ -156,13 +147,6 @@ void core_tmr_abort_task( se_cmd->state_active = false; spin_unlock_irqrestore(&dev->queues[i].lock, flags); - /* - * Ensure that this ABORT request is visible to the LU - * RESET code. - */ - if (!tmr->tmr_dev) - WARN_ON_ONCE(transport_lookup_tmr_lun(tmr->task_cmd) < 0); - if (dev->transport->tmr_notify) dev->transport->tmr_notify(dev, TMR_ABORT_TASK, &aborted_list); @@ -234,6 +218,7 @@ static void core_tmr_drain_tmr_list( } list_move_tail(&tmr_p->tmr_list, &drain_tmr_list); + tmr_p->tmr_dev = NULL; } spin_unlock_irqrestore(&dev->se_tmr_lock, flags); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 14c6f2bb1b01..e60abd230e90 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -676,6 +676,21 @@ static void target_remove_from_state_list(struct se_cmd *cmd) spin_unlock_irqrestore(&dev->queues[cmd->cpuid].lock, flags); } +static void target_remove_from_tmr_list(struct se_cmd *cmd) +{ + struct se_device *dev = NULL; + unsigned long flags; + + if (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) + dev = cmd->se_tmr_req->tmr_dev; + + if (dev) { + spin_lock_irqsave(&dev->se_tmr_lock, flags); + if (cmd->se_tmr_req->tmr_dev) + list_del_init(&cmd->se_tmr_req->tmr_list); + spin_unlock_irqrestore(&dev->se_tmr_lock, flags); + } +} /* * This function is called by the target core after the target core has * finished processing a SCSI command or SCSI TMF. Both the regular command @@ -687,13 +702,6 @@ static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd) { unsigned long flags; - target_remove_from_state_list(cmd); - - /* - * Clear struct se_cmd->se_lun before the handoff to FE. - */ - cmd->se_lun = NULL; - spin_lock_irqsave(&cmd->t_state_lock, flags); /* * Determine if frontend context caller is requesting the stopping of @@ -728,8 +736,16 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd) if (!lun) return; + target_remove_from_state_list(cmd); + target_remove_from_tmr_list(cmd); + if (cmpxchg(&cmd->lun_ref_active, true, false)) percpu_ref_put(&lun->lun_ref); + + /* + * Clear struct se_cmd->se_lun before the handoff to FE. + */ + cmd->se_lun = NULL; } static void target_complete_failure_work(struct work_struct *work)