linux-kernel - [PATCH 03/13] scsi: hisi_sas: Change common allocation mode of device id

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Date:   Mon, 21 May 2018 18:09:15 +0800
From:   John Garry <john.garry@...wei.com>
To:     <jejb@...ux.vnet.ibm.com>, <martin.petersen@...cle.com>
CC:     <linux-scsi@...r.kernel.org>, <linuxarm@...wei.com>,
        <linux-kernel@...r.kernel.org>,
        Xiang Chen <chenxiang66@...ilicon.com>,
        "John Garry" <john.garry@...wei.com>
Subject: [PATCH 03/13] scsi: hisi_sas: Change common allocation mode of device id

From: Xiang Chen <chenxiang66@...ilicon.com>

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@...ilicon.com>
Signed-off-by: John Garry <john.garry@...wei.com>
---
 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 3c88400..b4717bd 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 1d300a2..04a3eb4 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;
-- 
1.9.1