Revert "scsi: megaraid_sas: Added support for shared host tagset for cpuhotplug"

This reverts commit 103fbf8e.

It turns out that it causes long boot-time latencies (to the point of
timeouts and failed boots).

The cause is the increase in request queues, and a fix for that is
queued up for 5.11, but we're reverting this commit that triggered the
problem for now.
Reported-and-tested-by: NJohn Garry <john.garry@huawei.com>
Reported-and-tested-by: NJulia Lawall <julia.lawall@inria.fr>
Reported-by: NQian Cai <cai@redhat.com>
Acked-by: NJens Axboe <axboe@kernel.dk>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/linux-scsi/fe3dff7dae4494e5a88caffbb4d877bbf472dceb.camel@redhat.com/
Link: https://lore.kernel.org/lkml/alpine.DEB.2.22.394.2012081813310.2680@hadrien/
Link: https://lore.kernel.org/linux-block/20201203012638.543321-1-ming.lei@redhat.com/Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -37,7 +37,6 @@
 #include <linux/poll.h>
 #include <linux/vmalloc.h>
 #include <linux/irq_poll.h>
-#include <linux/blk-mq-pci.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -114,10 +113,6 @@ unsigned int enable_sdev_max_qd;
 module_param(enable_sdev_max_qd, int, 0444);
 MODULE_PARM_DESC(enable_sdev_max_qd, "Enable sdev max qd as can_queue. Default: 0");
 
-int host_tagset_enable = 1;
-module_param(host_tagset_enable, int, 0444);
-MODULE_PARM_DESC(host_tagset_enable, "Shared host tagset enable/disable Default: enable(1)");
-
 MODULE_LICENSE("GPL");
 MODULE_VERSION(MEGASAS_VERSION);
 MODULE_AUTHOR("megaraidlinux.pdl@broadcom.com");
@@ -3124,19 +3119,6 @@ megasas_bios_param(struct scsi_device *sdev, struct block_device *bdev,
 	return 0;
 }
 
-static int megasas_map_queues(struct Scsi_Host *shost)
-{
-	struct megasas_instance *instance;
-
-	instance = (struct megasas_instance *)shost->hostdata;
-
-	if (shost->nr_hw_queues == 1)
-		return 0;
-
-	return blk_mq_pci_map_queues(&shost->tag_set.map[HCTX_TYPE_DEFAULT],
-			instance->pdev, instance->low_latency_index_start);
-}
-
 static void megasas_aen_polling(struct work_struct *work);
 
 /**
@@ -3445,7 +3427,6 @@ static struct scsi_host_template megasas_template = {
 	.eh_timed_out = megasas_reset_timer,
 	.shost_attrs = megaraid_host_attrs,
 	.bios_param = megasas_bios_param,
-	.map_queues = megasas_map_queues,
 	.change_queue_depth = scsi_change_queue_depth,
 	.max_segment_size = 0xffffffff,
 };
@@ -6827,26 +6808,6 @@ static int megasas_io_attach(struct megasas_instance *instance)
 	host->max_lun = MEGASAS_MAX_LUN;
 	host->max_cmd_len = 16;
 
-	/* Use shared host tagset only for fusion adaptors
-	 * if there are managed interrupts (smp affinity enabled case).
-	 * Single msix_vectors in kdump, so shared host tag is also disabled.
-	 */
-
-	host->host_tagset = 0;
-	host->nr_hw_queues = 1;
-
-	if ((instance->adapter_type != MFI_SERIES) &&
-		(instance->msix_vectors > instance->low_latency_index_start) &&
-		host_tagset_enable &&
-		instance->smp_affinity_enable) {
-		host->host_tagset = 1;
-		host->nr_hw_queues = instance->msix_vectors -
-			instance->low_latency_index_start;
-	}
-
-	dev_info(&instance->pdev->dev,
-		"Max firmware commands: %d shared with nr_hw_queues = %d\n",
-		instance->max_fw_cmds, host->nr_hw_queues);
 	/*
 	 * Notify the mid-layer about the new controller
 	 */

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -359,29 +359,24 @@ megasas_get_msix_index(struct megasas_instance *instance,
 {
 	int sdev_busy;
 
-	/* TBD - if sml remove device_busy in future, driver
-	 * should track counter in internal structure.
-	 */
-	sdev_busy = atomic_read(&scmd->device->device_busy);
+	/* nr_hw_queue = 1 for MegaRAID */
+	struct blk_mq_hw_ctx *hctx =
+		scmd->device->request_queue->queue_hw_ctx[0];
+
+	sdev_busy = atomic_read(&hctx->nr_active);
 
 	if (instance->perf_mode == MR_BALANCED_PERF_MODE &&
-	    sdev_busy > (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH)) {
+	    sdev_busy > (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH))
 		cmd->request_desc->SCSIIO.MSIxIndex =
 			mega_mod64((atomic64_add_return(1, &instance->high_iops_outstanding) /
 					MR_HIGH_IOPS_BATCH_COUNT), instance->low_latency_index_start);
-	} else if (instance->msix_load_balance) {
+	else if (instance->msix_load_balance)
 		cmd->request_desc->SCSIIO.MSIxIndex =
 			(mega_mod64(atomic64_add_return(1, &instance->total_io_count),
 				instance->msix_vectors));
-	} else if (instance->host->nr_hw_queues > 1) {
-		u32 tag = blk_mq_unique_tag(scmd->request);
-
-		cmd->request_desc->SCSIIO.MSIxIndex = blk_mq_unique_tag_to_hwq(tag) +
-			instance->low_latency_index_start;
-	} else {
+	else
 		cmd->request_desc->SCSIIO.MSIxIndex =
 			instance->reply_map[raw_smp_processor_id()];
-	}
 }
 
 /**
@@ -961,6 +956,9 @@ megasas_alloc_cmds_fusion(struct megasas_instance *instance)
 	if (megasas_alloc_cmdlist_fusion(instance))
 		goto fail_exit;
 
+	dev_info(&instance->pdev->dev, "Configured max firmware commands: %d\n",
+		 instance->max_fw_cmds);
+
 	/* The first 256 bytes (SMID 0) is not used. Don't add to the cmd list */
 	io_req_base = fusion->io_request_frames + MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE;
 	io_req_base_phys = fusion->io_request_frames_phys + MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE;
@@ -1104,9 +1102,8 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
 		MR_HIGH_IOPS_QUEUE_COUNT) && cur_intr_coalescing)
 		instance->perf_mode = MR_BALANCED_PERF_MODE;
 
-	dev_info(&instance->pdev->dev, "Performance mode :%s (latency index = %d)\n",
-		MEGASAS_PERF_MODE_2STR(instance->perf_mode),
-		instance->low_latency_index_start);
+	dev_info(&instance->pdev->dev, "Performance mode :%s\n",
+		MEGASAS_PERF_MODE_2STR(instance->perf_mode));
 
 	instance->fw_sync_cache_support = (scratch_pad_1 &
 		MR_CAN_HANDLE_SYNC_CACHE_OFFSET) ? 1 : 0;