Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull more SCSI updates from James Bottomley:
 "Mostly small bug fixes and trivial updates.

  The major new core update is a change to the way device, target and
  host reference counting is done to try to make it more robust (this
  change has soaked for a while to try to winkle out any bugs)"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: pm8001: Fix typo 'the the' in comment
  scsi: megaraid_sas: Remove redundant variable cmd_type
  scsi: FlashPoint: Remove redundant variable bm_int_st
  scsi: zfcp: Fix missing auto port scan and thus missing target ports
  scsi: core: Call blk_mq_free_tag_set() earlier
  scsi: core: Simplify LLD module reference counting
  scsi: core: Make sure that hosts outlive targets
  scsi: core: Make sure that targets outlive devices
  scsi: ufs: ufs-pci: Correct check for RESET DSM
  scsi: target: core: De-RCU of se_lun and se_lun acl
  scsi: target: core: Fix race during ACL removal
  scsi: ufs: core: Correct ufshcd_shutdown() flow
  scsi: ufs: core: Increase the maximum data buffer size
  scsi: lpfc: Check the return value of alloc_workqueue()

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index aa70d9282161..9dad2fd5297f 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -443,18 +443,15 @@ static void scsi_device_cls_release(struct device *class_dev)
 
 static void scsi_device_dev_release_usercontext(struct work_struct *work)
 {
-	struct scsi_device *sdev;
+	struct scsi_device *sdev = container_of(work, struct scsi_device,
+						ew.work);
+	struct scsi_target *starget = sdev->sdev_target;
 	struct device *parent;
 	struct list_head *this, *tmp;
 	struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
 	struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL;
 	struct scsi_vpd *vpd_pgb0 = NULL, *vpd_pgb1 = NULL, *vpd_pgb2 = NULL;
 	unsigned long flags;
-	struct module *mod;
-
-	sdev = container_of(work, struct scsi_device, ew.work);
-
-	mod = sdev->host->hostt->module;
 
 	scsi_dh_release_device(sdev);
 
@@ -516,19 +513,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 	kfree(sdev->inquiry);
 	kfree(sdev);
 
+	if (starget && atomic_dec_return(&starget->sdev_count) == 0)
+		wake_up(&starget->sdev_wq);
+
 	if (parent)
 		put_device(parent);
-	module_put(mod);
 }
 
 static void scsi_device_dev_release(struct device *dev)
 {
 	struct scsi_device *sdp = to_scsi_device(dev);
-
-	/* Set module pointer as NULL in case of module unloading */
-	if (!try_module_get(sdp->host->hostt->module))
-		sdp->host->hostt->module = NULL;
-
 	execute_in_process_context(scsi_device_dev_release_usercontext,
 				   &sdp->ew);
 }
@@ -1535,6 +1529,14 @@ static void __scsi_remove_target(struct scsi_target *starget)
 		goto restart;
 	}
 	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	/*
+	 * After scsi_remove_target() returns its caller can remove resources
+	 * associated with @starget, e.g. an rport or session. Wait until all
+	 * devices associated with @starget have been removed to prevent that
+	 * a SCSI error handling callback function triggers a use-after-free.
+	 */
+	wait_event(starget->sdev_wq, atomic_read(&starget->sdev_count) == 0);
 }
 
 /**
@@ -1645,6 +1647,9 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev)
 	list_add_tail(&sdev->same_target_siblings, &starget->devices);
 	list_add_tail(&sdev->siblings, &shost->__devices);
 	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	atomic_inc(&starget->sdev_count);
+
 	/*
 	 * device can now only be removed via __scsi_remove_device() so hold
 	 * the target.  Target will be held in CREATED state until something