block: remove parent device reference from struct bsg_class_device

Bsg holding a reference to the parent device may result in a crash if a
bsg file handle is closed after the parent device driver has unloaded.

Holding a reference is not really needed: the parent device must exist
between bsg_register_queue and bsg_unregister_queue.  Before the device
goes away the caller does blk_cleanup_queue so that all in-flight
requests to the device are gone and all new requests cannot pass beyond
the queue.  The queue itself is a refcounted object and it will stay
alive with a bsg file.

Based on analysis, previous patch and changelog from Anatoliy Glagolev.

Reported-by: Anatoliy Glagolev <glagolig@gmail.com>
Reviewed-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 10 insertions, 18 deletions

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 7a9a65588a1b..1da3d71e9f61 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -3780,8 +3780,7 @@ fc_bsg_hostadd(struct Scsi_Host *shost, struct fc_host_attrs *fc_host)
 	snprintf(bsg_name, sizeof(bsg_name),
 		 "fc_host%d", shost->host_no);
 
-	q = bsg_setup_queue(dev, bsg_name, fc_bsg_dispatch, i->f->dd_bsg_size,
-			NULL);
+	q = bsg_setup_queue(dev, bsg_name, fc_bsg_dispatch, i->f->dd_bsg_size);
 	if (IS_ERR(q)) {
 		dev_err(dev,
 			"fc_host%d: bsg interface failed to initialize - setup queue\n",
@@ -3826,8 +3825,8 @@ fc_bsg_rportadd(struct Scsi_Host *shost, struct fc_rport *rport)
 	if (!i->f->bsg_request)
 		return -ENOTSUPP;
 
-	q = bsg_setup_queue(dev, NULL, fc_bsg_dispatch, i->f->dd_bsg_size,
-			NULL);
+	q = bsg_setup_queue(dev, dev_name(dev), fc_bsg_dispatch,
+			i->f->dd_bsg_size);
 	if (IS_ERR(q)) {
 		dev_err(dev, "failed to setup bsg queue\n");
 		return PTR_ERR(q);
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 65f6c94f2e9b..6fd2fe210fc3 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1542,7 +1542,7 @@ iscsi_bsg_host_add(struct Scsi_Host *shost, struct iscsi_cls_host *ihost)
 		return -ENOTSUPP;
 
 	snprintf(bsg_name, sizeof(bsg_name), "iscsi_host%d", shost->host_no);
-	q = bsg_setup_queue(dev, bsg_name, iscsi_bsg_host_dispatch, 0, NULL);
+	q = bsg_setup_queue(dev, bsg_name, iscsi_bsg_host_dispatch, 0);
 	if (IS_ERR(q)) {
 		shost_printk(KERN_ERR, shost, "bsg interface failed to "
 			     "initialize - no request queue\n");
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 08acbabfae07..e2953b416746 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -187,16 +187,6 @@ static int sas_smp_dispatch(struct bsg_job *job)
 	return 0;
 }
 
-static void sas_host_release(struct device *dev)
-{
-	struct Scsi_Host *shost = dev_to_shost(dev);
-	struct sas_host_attrs *sas_host = to_sas_host_attrs(shost);
-	struct request_queue *q = sas_host->q;
-
-	if (q)
-		blk_cleanup_queue(q);
-}
-
 static int sas_bsg_initialize(struct Scsi_Host *shost, struct sas_rphy *rphy)
 {
 	struct request_queue *q;
@@ -208,7 +198,7 @@ static int sas_bsg_initialize(struct Scsi_Host *shost, struct sas_rphy *rphy)
 
 	if (rphy) {
 		q = bsg_setup_queue(&rphy->dev, dev_name(&rphy->dev),
-				sas_smp_dispatch, 0, NULL);
+				sas_smp_dispatch, 0);
 		if (IS_ERR(q))
 			return PTR_ERR(q);
 		rphy->q = q;
@@ -217,7 +207,7 @@ static int sas_bsg_initialize(struct Scsi_Host *shost, struct sas_rphy *rphy)
 
 		snprintf(name, sizeof(name), "sas_host%d", shost->host_no);
 		q = bsg_setup_queue(&shost->shost_gendev, name,
-				sas_smp_dispatch, 0, sas_host_release);
+				sas_smp_dispatch, 0);
 		if (IS_ERR(q))
 			return PTR_ERR(q);
 		to_sas_host_attrs(shost)->q = q;
@@ -260,8 +250,11 @@ static int sas_host_remove(struct transport_container *tc, struct device *dev,
 	struct Scsi_Host *shost = dev_to_shost(dev);
 	struct request_queue *q = to_sas_host_attrs(shost)->q;
 
-	if (q)
+	if (q) {
 		bsg_unregister_queue(q);
+		blk_cleanup_queue(q);
+	}
+
 	return 0;
 }