On Wed, 2017-05-24 at 07:51 +0200, Hannes Reinecke wrote:

On 05/24/2017 02:33 AM, Bart Van Assche wrote:

quoted

Enable this mechanism for all scsi_target_*block() callers but not
for the scsi_internal_device_unblock() calls from the mpt3sas driver
because that driver can call scsi_internal_device_unblock() from
atomic context.
=20
Signed-off-by: Bart Van Assche <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <redacted>
---
 drivers/scsi/scsi_error.c         |  8 +++++++-
 drivers/scsi/scsi_lib.c           | 27 +++++++++++++++++++++------
 drivers/scsi/scsi_scan.c          | 16 +++++++++-------
 drivers/scsi/scsi_sysfs.c         | 24 +++++++++++++++++++-----
 drivers/scsi/scsi_transport_srp.c |  7 ++++---
 drivers/scsi/sd.c                 |  7 +++++--
 include/scsi/scsi_device.h        |  1 +
 7 files changed, 66 insertions(+), 24 deletions(-)
=20

=20
[ .. ]

quoted

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_tran=

sport_srp.c

quoted

index 3c5d89852e9f..f617021c94f7 100644

--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c

@@ -554,11 +554,12 @@ int srp_reconnect_rport(struct srp_rport *rport)
 		 * invoking scsi_target_unblock() won't change the state of
 		 * these devices into running so do that explicitly.
 		 */
-		spin_lock_irq(shost->host_lock);
-		__shost_for_each_device(sdev, shost)
+		shost_for_each_device(sdev, shost) {
+			mutex_lock(&sdev->state_mutex);
 			if (sdev->sdev_state =3D=3D SDEV_OFFLINE)
 				sdev->sdev_state =3D SDEV_RUNNING;
-		spin_unlock_irq(shost->host_lock);
+			mutex_unlock(&sdev->state_mutex);
+		}
 	} else if (rport->state =3D=3D SRP_RPORT_RUNNING) {
 		/*
 		 * srp_reconnect_rport() has been invoked with fast_io_fail

=20
Why do you drop the host lock here? I thought that the host lock is
needed to protect shost_for_each_device()?

Hello Hannes,

The only purpose of holding the host lock was to protect the SCSI device li=
st
iteration by __shost_for_each_device(). shost_for_each_device() obtains tha=
t
lock itself. From <scsi/scsi_device.h>:

#define shost_for_each_device(sdev, shost) \
	for ((sdev) =3D __scsi_iterate_devices((shost), NULL); \
	=A0=A0=A0=A0=A0(sdev); \
	=A0=A0=A0=A0=A0(sdev) =3D __scsi_iterate_devices((shost), (sdev)))

From drivers/scsi/scsi.c:

struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
					=A0=A0=A0struct scsi_device *prev)
{
	struct list_head *list =3D (prev ? &prev->siblings : &shost->__devices);
	struct scsi_device *next =3D NULL;
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	while (list->next !=3D &shost->__devices) {
		next =3D list_entry(list->next, struct scsi_device, siblings);
		/* skip devices that we can't get a reference to */
		if (!scsi_device_get(next))
			break;
		next =3D NULL;
		list =3D list->next;
	}
	spin_unlock_irqrestore(shost->host_lock, flags);

	if (prev)
		scsi_device_put(prev);
	return next;
}

Bart.=