From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40jKKZ6gcnzF2rs for ; Sat, 12 May 2018 05:05:06 +1000 (AEST) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w4BIx11f118940 for ; Fri, 11 May 2018 15:05:04 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hwfkgucj7-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 11 May 2018 15:05:03 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 11 May 2018 15:05:02 -0400 From: Uma Krishnan To: linux-scsi@vger.kernel.org, James Bottomley , "Martin K. Petersen" , "Matthew R. Ochs" , "Manoj N. Kumar" Cc: linuxppc-dev@lists.ozlabs.org, Andrew Donnellan , Frederic Barrat , Christophe Lombard Subject: [PATCH 1/7] cxlflash: Yield to active send threads Date: Fri, 11 May 2018 14:04:46 -0500 In-Reply-To: <1526065440-38806-1-git-send-email-ukrishn@linux.vnet.ibm.com> References: <1526065440-38806-1-git-send-email-ukrishn@linux.vnet.ibm.com> Message-Id: <1526065486-38860-1-git-send-email-ukrishn@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , The following Oops may be encountered if the device is reset, i.e. EEH recovery, while there is heavy I/O traffic: 59:mon> t [c000200db64bb680] c008000009264c40 cxlflash_queuecommand+0x3b8/0x500 [cxlflash] [c000200db64bb770] c00000000090d3b0 scsi_dispatch_cmd+0x130/0x2f0 [c000200db64bb7f0] c00000000090fdd8 scsi_request_fn+0x3c8/0x8d0 [c000200db64bb900] c00000000067f528 __blk_run_queue+0x68/0xb0 [c000200db64bb930] c00000000067ab80 __elv_add_request+0x140/0x3c0 [c000200db64bb9b0] c00000000068daac blk_execute_rq_nowait+0xec/0x1a0 [c000200db64bba00] c00000000068dbb0 blk_execute_rq+0x50/0xe0 [c000200db64bba50] c0000000006b2040 sg_io+0x1f0/0x520 [c000200db64bbaf0] c0000000006b2e94 scsi_cmd_ioctl+0x534/0x610 [c000200db64bbc20] c000000000926208 sd_ioctl+0x118/0x280 [c000200db64bbcc0] c00000000069f7ac blkdev_ioctl+0x7fc/0xe30 [c000200db64bbd20] c000000000439204 block_ioctl+0x84/0xa0 [c000200db64bbd40] c0000000003f8514 do_vfs_ioctl+0xd4/0xa00 [c000200db64bbde0] c0000000003f8f04 SyS_ioctl+0xc4/0x130 [c000200db64bbe30] c00000000000b184 system_call+0x58/0x6c When there is no room to send the I/O request, the cached room is refreshed by reading the memory mapped command room value from the AFU. The AFU register mapping is refreshed during a reset, creating a race condition that can lead to the Oops above. During a device reset, the AFU should not be unmapped until all the active send threads quiesce. An atomic counter, cmds_active, is currently used to track internal AFU commands and quiesce during reset. This same counter can also be used for the active send threads. Signed-off-by: Uma Krishnan --- drivers/scsi/cxlflash/main.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c index a24d7e6..dad2be6 100644 --- a/drivers/scsi/cxlflash/main.c +++ b/drivers/scsi/cxlflash/main.c @@ -616,6 +616,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) rc = 0; goto out; default: + atomic_inc(&afu->cmds_active); break; } @@ -641,6 +642,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) memcpy(cmd->rcb.cdb, scp->cmnd, sizeof(cmd->rcb.cdb)); rc = afu->send_cmd(afu, cmd); + atomic_dec(&afu->cmds_active); out: return rc; } -- 2.1.0