linux-kernel - [PATCH 3/4] scsi: pm8001: Use non-atomic bitmap ops for tag alloc + free

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Message-ID: <1654879602-33497-4-git-send-email-john.garry@huawei.com>
Date:   Sat, 11 Jun 2022 00:46:41 +0800
From:   John Garry <john.garry@...wei.com>
To:     <jinpu.wang@...ud.ionos.com>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>
CC:     <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <hare@...e.de>, <damien.lemoal@...nsource.wdc.com>,
        <Ajish.Koshy@...rochip.com>, John Garry <john.garry@...wei.com>
Subject: [PATCH 3/4] scsi: pm8001: Use non-atomic bitmap ops for tag alloc + free

In pm8001_tag_alloc() we don't require atomic set_bit() as we are already
in atomic context. In pm8001_tag_free() we should use the same host
spinlock to protect clearing the tag (and then don't require the atomic
clear_bit()).

Signed-off-by: John Garry <john.garry@...wei.com>
---
 drivers/scsi/pm8001/pm8001_sas.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
index 3a863d776724..8e3f2f9ddaac 100644
--- a/drivers/scsi/pm8001/pm8001_sas.c
+++ b/drivers/scsi/pm8001/pm8001_sas.c
@@ -66,7 +66,11 @@ static int pm8001_find_tag(struct sas_task *task, u32 *tag)
 void pm8001_tag_free(struct pm8001_hba_info *pm8001_ha, u32 tag)
 {
 	void *bitmap = pm8001_ha->tags;
-	clear_bit(tag, bitmap);
+	unsigned long flags;
+
+	spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
+	__clear_bit(tag, bitmap);
+	spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
 }
 
 /**
@@ -76,9 +80,9 @@ void pm8001_tag_free(struct pm8001_hba_info *pm8001_ha, u32 tag)
   */
 int pm8001_tag_alloc(struct pm8001_hba_info *pm8001_ha, u32 *tag_out)
 {
-	unsigned int tag;
 	void *bitmap = pm8001_ha->tags;
 	unsigned long flags;
+	unsigned int tag;
 
 	spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
 	tag = find_first_zero_bit(bitmap, pm8001_ha->tags_num);
@@ -86,7 +90,7 @@ int pm8001_tag_alloc(struct pm8001_hba_info *pm8001_ha, u32 *tag_out)
 		spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
 		return -SAS_QUEUE_FULL;
 	}
-	set_bit(tag, bitmap);
+	__set_bit(tag, bitmap);
 	spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
 	*tag_out = tag;
 	return 0;
-- 
2.26.2