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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
To:     jejb@linux.ibm.com, martin.petersen@oracle.com
Cc:     acelan.kao@canonical.com,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] scsi: core: Avoid doing rescan on suspended device
Date:   Wed, 19 Apr 2023 13:41:12 +0800
Message-Id: <20230419054112.269734-1-kai.heng.feng@canonical.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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During system resume, if an EH is schduled after ATA host is resumed
(i.e. ATA_PFLAG_PM_PENDING cleared), but before the disk device is
resumed, the device_lock hold by scsi_rescan_device() is never released
so the dpm_resume() of the disk is blocked forerver.

That's because scsi_attach_vpd() is expecting the disk device is in
operational state, as it doesn't work on suspended device.

To avoid such deadlock, avoid doing rescan if the disk is still
suspended so the resume process of the disk device can proceed.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/scsi/scsi_scan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index d217be323cc6..36680cb1535b 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1621,6 +1621,9 @@ void scsi_rescan_device(struct device *dev)
 {
 	struct scsi_device *sdev = to_scsi_device(dev);
 
+	if (dev->power.is_prepared)
+		return;
+
 	device_lock(dev);
 
 	scsi_attach_vpd(sdev);
-- 
2.34.1