Commit ff48b37802e5c134e2dfc4d091f10b2eb5065a72 upstream.
scsi_rescan_device() takes a scsi device lock before executing a device
handler and device driver rescan methods. Waiting for the completion of
any command issued to the device by these methods will thus be done with
the device lock held. As a result, there is a risk of deadlocking within
the power management code if scsi_rescan_device() is called to handle a
device resume with the associated scsi device not yet resumed.
Avoid such situation by checking that the target scsi device is in the
running state, that is, fully capable of executing commands, before
proceeding with the rescan and bailout returning -EWOULDBLOCK otherwise.
With this error return, the caller can retry rescaning the device after
a delay.
The state check is done with the device lock held and is thus safe
against incoming suspend power management operations.
Fixes: 6aa0365a3c85 ("ata: libata-scsi: Avoid deadlock on rescan after device resume")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Reviewed-by: Niklas Cassel <niklas.cassel@xxxxxxx>
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
(cherry picked from commit ff48b37802e5c134e2dfc4d091f10b2eb5065a72)
---
drivers/scsi/scsi_priv.h | 2 +-
drivers/scsi/scsi_scan.c | 18 +++++++++++++++++-
include/scsi/scsi_host.h | 2 +-
3 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index f42388ecb024..30861e7e6850 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -138,7 +138,7 @@ extern int scsi_complete_async_scans(void);
extern int scsi_scan_host_selected(struct Scsi_Host *, unsigned int,
unsigned int, u64, enum scsi_scan_mode);
extern void scsi_forget_host(struct Scsi_Host *);
-extern void scsi_rescan_device(struct device *);
+extern int scsi_rescan_device(struct device *dev);
/* scsi_sysctl.c */
#ifdef CONFIG_SYSCTL
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index aa13feb17c62..5d4d3d48e3f0 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1619,12 +1619,24 @@ int scsi_add_device(struct Scsi_Host *host, uint channel,
}
EXPORT_SYMBOL(scsi_add_device);
-void scsi_rescan_device(struct device *dev)
+int scsi_rescan_device(struct device *dev)
{
struct scsi_device *sdev = to_scsi_device(dev);
+ int ret = 0;
device_lock(dev);
+ /*
+ * Bail out if the device is not running. Otherwise, the rescan may
+ * block waiting for commands to be executed, with us holding the
+ * device lock. This can result in a potential deadlock in the power
+ * management core code when system resume is on-going.
+ */
+ if (sdev->sdev_state != SDEV_RUNNING) {
+ ret = -EWOULDBLOCK;
+ goto unlock;
+ }
+
scsi_attach_vpd(sdev);
scsi_cdl_check(sdev);
@@ -1638,7 +1650,11 @@ void scsi_rescan_device(struct device *dev)
drv->rescan(dev);
module_put(dev->driver->owner);
}
+
+unlock:
device_unlock(dev);
+
+ return ret;
}
EXPORT_SYMBOL(scsi_rescan_device);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index a2b8d30c4c80..4fa55d88d492 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -764,7 +764,7 @@ scsi_template_proc_dir(const struct scsi_host_template *sht);
#define scsi_template_proc_dir(sht) NULL
#endif
extern void scsi_scan_host(struct Scsi_Host *);
-extern void scsi_rescan_device(struct device *);
+extern int scsi_rescan_device(struct device *dev);
extern void scsi_remove_host(struct Scsi_Host *);
extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
extern int scsi_host_busy(struct Scsi_Host *shost);
--
2.41.0
