From patchwork Thu Jun 25 14:01:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hannes Reinecke X-Patchwork-Id: 11625455 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BA21714B7 for ; Thu, 25 Jun 2020 14:02:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA4D820702 for ; Thu, 25 Jun 2020 14:02:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405333AbgFYOCG (ORCPT ); Thu, 25 Jun 2020 10:02:06 -0400 Received: from mx2.suse.de ([195.135.220.15]:41254 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405145AbgFYOBt (ORCPT ); Thu, 25 Jun 2020 10:01:49 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C890CAEBE; Thu, 25 Jun 2020 14:01:45 +0000 (UTC) From: Hannes Reinecke To: "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , John Garry , Don Brace , Bart van Assche , linux-scsi@vger.kernel.org, Hannes Reinecke Subject: [PATCH 08/22] scsi: implement reserved command handling Date: Thu, 25 Jun 2020 16:01:10 +0200 Message-Id: <20200625140124.17201-9-hare@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20200625140124.17201-1-hare@suse.de> References: <20200625140124.17201-1-hare@suse.de> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Quite some drivers are using management commands internally, which typically use the same hardware tag pool (ie they are being allocated from the same hardware resources) as the 'normal' I/O commands. These commands are set aside before allocating the block-mq tag bitmap, so they'll never show up as busy in the tag map. The block-layer, OTOH, already has 'reserved_tags' to handle precisely this situation. So this patch adds a new field 'nr_reserved_cmds' to the SCSI host template to instruct the block layer to set aside a tag space for these management commands by using reserved tags. Signed-off-by: Hannes Reinecke --- drivers/scsi/scsi_lib.c | 10 +++++++++- include/scsi/scsi_host.h | 11 +++++++++++ 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index bd378e1bd3fc..a752806af70b 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1887,7 +1887,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) else tag_set->ops = &scsi_mq_ops_no_commit; tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; - tag_set->queue_depth = shost->can_queue; + tag_set->queue_depth = + shost->can_queue + shost->nr_reserved_cmds; + tag_set->reserved_tags = shost->nr_reserved_cmds; tag_set->cmd_size = cmd_size; tag_set->numa_node = NUMA_NO_NODE; tag_set->flags = BLK_MQ_F_SHOULD_MERGE; @@ -1910,6 +1912,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) * @op_flags: request allocation flags * * Allocates a SCSI command for internal LLDD use. + * If 'nr_reserved_commands' is spectified by the host the + * command will be allocated from the reserved tag pool; + * otherwise the normal tag pool will be used. */ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, int data_direction, int op_flags) @@ -1919,6 +1924,9 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, blk_mq_req_flags_t flags = 0; unsigned int op = REQ_INTERNAL | op_flags; + if (sdev->host->nr_reserved_cmds) + flags = BLK_MQ_REQ_RESERVED; + op |= (data_direction == DMA_TO_DEVICE) ? REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN; rq = blk_mq_alloc_request(sdev->request_queue, op, flags); diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 46ef8cccc982..b94938e87e3a 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -590,6 +590,11 @@ struct Scsi_Host { unsigned short max_cmd_len; int this_id; + + /* + * Number of commands this host can handle at the same time. + * This excludes reserved commands as specified by nr_reserved_cmds. + */ int can_queue; short cmd_per_lun; short unsigned int sg_tablesize; @@ -606,6 +611,12 @@ struct Scsi_Host { * is nr_hw_queues * can_queue. */ unsigned nr_hw_queues; + + /* + * Number of reserved commands to allocate, if any. + */ + unsigned nr_reserved_cmds; + unsigned active_mode:2; unsigned unchecked_isa_dma:1;