From: Xiang Chen <chenxiang66@hisilicon.com>
Date: Mon, 21 May 2018 18:09:15 +0800
Subject: scsi: hisi_sas: Change common allocation mode of device id
Git-commit: 1b86518581f6111f5996ff8d4304bde2e3b05eb9
Patch-mainline: v4.18-rc1
References: FATE#326253

To reduce possibility of hitting unknown SoC bugs and aid debugging and
test, change allocation mode of device id from last used device id instead
of lowest available index.

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/scsi/hisi_sas/hisi_sas.h      | 1 +
 drivers/scsi/hisi_sas/hisi_sas_main.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
index 3c8840089cd5..b4717bd8af3f 100644
--- a/drivers/scsi/hisi_sas/hisi_sas.h
+++ b/drivers/scsi/hisi_sas/hisi_sas.h
@@ -275,6 +275,7 @@ struct hisi_hba {
 
 	int slot_index_count;
 	int last_slot_index;
+	int last_dev_id;
 	unsigned long *slot_index_tags;
 	unsigned long reject_stp_links_msk;
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 796fdfc73c75..a7e4c6e77068 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -596,10 +596,12 @@ static struct hisi_sas_device *hisi_sas_alloc_dev(struct domain_device *device)
 	struct hisi_hba *hisi_hba = dev_to_hisi_hba(device);
 	struct hisi_sas_device *sas_dev = NULL;
 	unsigned long flags;
+	int last = hisi_hba->last_dev_id;
+	int first = (hisi_hba->last_dev_id + 1) % HISI_SAS_MAX_DEVICES;
 	int i;
 
 	spin_lock_irqsave(&hisi_hba->lock, flags);
-	for (i = 0; i < HISI_SAS_MAX_DEVICES; i++) {
+	for (i = first; i != last; i %= HISI_SAS_MAX_DEVICES) {
 		if (hisi_hba->devices[i].dev_type == SAS_PHY_UNUSED) {
 			int queue = i % hisi_hba->queue_count;
 			struct hisi_sas_dq *dq = &hisi_hba->dq[queue];
@@ -614,7 +616,9 @@ static struct hisi_sas_device *hisi_sas_alloc_dev(struct domain_device *device)
 			INIT_LIST_HEAD(&hisi_hba->devices[i].list);
 			break;
 		}
+		i++;
 	}
+	hisi_hba->last_dev_id = i;
 	spin_unlock_irqrestore(&hisi_hba->lock, flags);
 
 	return sas_dev;