Comment provided by Bart Van and Chris H is addressed in this patch. Add use_cmd_list flag in scsi_host to indicate scs.mq stack to keep track of cmd_list per sdev.
Default behaviour is not to keep track of cmd_list per sdev, as this may introduce lock contention. (overhead is more on multi-node NUMA.) Patch is tested using megaraid_sas driver with "use_cmd_list" value set to 1 and 0. Added MAINTAINER of Adaptec to verify changes. Signed-off-by: Kashyap Desai <[email protected]> -- diff --git a/drivers/scsi/aacraid/linit.c b/drivers/scsi/aacraid/linit.c index 63f576c..a759cb2 100644 --- a/drivers/scsi/aacraid/linit.c +++ b/drivers/scsi/aacraid/linit.c @@ -1152,6 +1152,7 @@ static int aac_probe_one(struct pci_dev *pdev, const struct pci_device_id *id) shost->irq = pdev->irq; shost->unique_id = unique_id; shost->max_cmd_len = 16; + shost->use_cmd_list = 1; aac = (struct aac_dev *)shost->hostdata; aac->base_start = pci_resource_start(pdev, 0); diff --git a/drivers/scsi/dpt_i2o.c b/drivers/scsi/dpt_i2o.c index 67283ef..072f0ec 100644 --- a/drivers/scsi/dpt_i2o.c +++ b/drivers/scsi/dpt_i2o.c @@ -2363,6 +2363,7 @@ static s32 adpt_scsi_host_alloc(adpt_hba* pHba, struct scsi_host_template *sht) host->unique_id = (u32)sys_tbl_pa + pHba->unit; host->sg_tablesize = pHba->sg_tablesize; host->can_queue = pHba->post_fifo_size; + host->use_cmd_list = 1; return 0; } diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9c44392..f9ce306 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -645,16 +645,18 @@ static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd) static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) { struct scsi_device *sdev = cmd->device; + struct Scsi_Host *shost = sdev->host; unsigned long flags; - BUG_ON(list_empty(&cmd->list)); - scsi_mq_free_sgtables(cmd); scsi_uninit_cmd(cmd); - spin_lock_irqsave(&sdev->list_lock, flags); - list_del_init(&cmd->list); - spin_unlock_irqrestore(&sdev->list_lock, flags); + if (shost->use_cmd_list) { + BUG_ON(list_empty(&cmd->list)); + spin_lock_irqsave(&sdev->list_lock, flags); + list_del_init(&cmd->list); + spin_unlock_irqrestore(&sdev->list_lock, flags); + } } /* @@ -1815,14 +1817,12 @@ static int scsi_mq_prep_fn(struct request *req) INIT_LIST_HEAD(&cmd->list); INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); cmd->jiffies_at_alloc = jiffies; - - /* - * XXX: cmd_list lookups are only used by two drivers, try to get - * rid of this list in common code. - */ - spin_lock_irq(&sdev->list_lock); - list_add_tail(&cmd->list, &sdev->cmd_list); - spin_unlock_irq(&sdev->list_lock); + + if (shost->use_cmd_list) { + spin_lock_irq(&sdev->list_lock); + list_add_tail(&cmd->list, &sdev->cmd_list); + spin_unlock_irq(&sdev->list_lock); + } sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size; cmd->sdb.table.sgl = sg; diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index ba20347..cafb260 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -680,6 +680,7 @@ struct Scsi_Host { unsigned no_write_same:1; unsigned use_blk_mq:1; + unsigned use_cmd_list:1; /* * Optional work queue to be utilized by the transport -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
