From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:45404 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933183AbcILRKG (ORCPT ); Mon, 12 Sep 2016 13:10:06 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Manoj N. Kumar" , "Matthew R. Ochs" , Uma Krishnan , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 4.4 096/192] [PATCH 100/135] cxlflash: Fix to avoid unnecessary scan with internal LUNs Date: Mon, 12 Sep 2016 19:00:05 +0200 Message-Id: <20160912152202.966835764@linuxfoundation.org> In-Reply-To: <20160912152158.855601725@linuxfoundation.org> References: <20160912152158.855601725@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 603ecce95f4817074a724a889cd88c3c8210f933 ] When switching to the internal LUN defined on the IBM CXL flash adapter, there is an unnecessary scan occurring on the second port. This scan leads to the following extra lines in the log: Dec 17 10:09:00 tul83p1 kernel: [ 3708.561134] cxlflash 0008:00:00.0: cxlflash_queuecommand: (scp=c0000000fc1f0f00) 11/1/0/0 cdb=(A0000000-00000000-10000000-00000000) Dec 17 10:09:00 tul83p1 kernel: [ 3708.561147] process_cmd_err: cmd failed afu_rc=32 scsi_rc=0 fc_rc=0 afu_extra=0xE, scsi_extra=0x0, fc_extra=0x0 By definition, both of the internal LUNs are on the first port/channel. When the lun_mode is switched to internal LUN the same value for host->max_channel is retained. This causes an unnecessary scan over the second port/channel. This fix alters the host->max_channel to 0 (1 port), if internal LUNs are configured and switches it back to 1 (2 ports) while going back to external LUNs. Signed-off-by: Manoj N. Kumar Acked-by: Matthew R. Ochs Reviewed-by: Uma Krishnan Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/cxlflash/main.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/scsi/cxlflash/main.c +++ b/drivers/scsi/cxlflash/main.c @@ -2149,6 +2149,16 @@ static ssize_t lun_mode_store(struct dev rc = kstrtouint(buf, 10, &lun_mode); if (!rc && (lun_mode < 5) && (lun_mode != afu->internal_lun)) { afu->internal_lun = lun_mode; + + /* + * When configured for internal LUN, there is only one channel, + * channel number 0, else there will be 2 (default). + */ + if (afu->internal_lun) + shost->max_channel = 0; + else + shost->max_channel = NUM_FC_PORTS - 1; + afu_reset(cfg); scsi_scan_host(cfg->host); }