return found_starget;
}
+/**
+ * scsi_target_reap_ref_release - remove target from visibility
+ * @kref: the reap_ref in the target being released
+ *
+ * Called on last put of reap_ref, which is the indication that no device
+ * under this target is visible anymore, so render the target invisible in
+ * sysfs. Note: we have to be in user context here because the target reaps
+ * should be done in places where the scsi device visibility is being removed.
+ */
+static void scsi_target_reap_ref_release(struct kref *kref)
+{
+ struct scsi_target *starget
+ = container_of(kref, struct scsi_target, reap_ref);
+
+ transport_remove_device(&starget->dev);
+ device_del(&starget->dev);
+ starget->state = STARGET_DEL;
+ scsi_target_destroy(starget);
+}
+
+static void scsi_target_reap_ref_put(struct scsi_target *starget)
+{
+ kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
+}
+
/**
* scsi_alloc_target - allocate a new or find an existing target
* @parent: parent of the target (need not be a scsi host)
+ shost->transportt->target_size;
struct scsi_target *starget;
struct scsi_target *found_target;
- int error;
+ int error, ref_got;
starget = kzalloc(size, GFP_KERNEL);
if (!starget) {
}
dev = &starget->dev;
device_initialize(dev);
- starget->reap_ref = 1;
+ kref_init(&starget->reap_ref);
dev->parent = get_device(parent);
dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
dev->bus = &scsi_bus_type;
return starget;
found:
- found_target->reap_ref++;
+ /*
+ * release routine already fired if kref is zero, so if we can still
+ * take the reference, the target must be alive. If we can't, it must
+ * be dying and we need to wait for a new target
+ */
+ ref_got = kref_get_unless_zero(&found_target->reap_ref);
+
spin_unlock_irqrestore(shost->host_lock, flags);
- if (found_target->state != STARGET_DEL) {
+ if (ref_got) {
put_device(dev);
return found_target;
}
- /* Unfortunately, we found a dying target; need to
- * wait until it's dead before we can get a new one */
+ /*
+ * Unfortunately, we found a dying target; need to wait until it's
+ * dead before we can get a new one. There is an anomaly here. We
+ * *should* call scsi_target_reap() to balance the kref_get() of the
+ * reap_ref above. However, since the target being released, it's
+ * already invisible and the reap_ref is irrelevant. If we call
+ * scsi_target_reap() we might spuriously do another device_del() on
+ * an already invisible target.
+ */
put_device(&found_target->dev);
- flush_scheduled_work();
+ /*
+ * length of time is irrelevant here, we just want to yield the CPU
+ * for a tick to avoid busy waiting for the target to die.
+ */
+ msleep(1);
goto retry;
}
-static void scsi_target_reap_usercontext(struct work_struct *work)
-{
- struct scsi_target *starget =
- container_of(work, struct scsi_target, ew.work);
-
- transport_remove_device(&starget->dev);
- device_del(&starget->dev);
- scsi_target_destroy(starget);
-}
-
/**
* scsi_target_reap - check to see if target is in use and destroy if not
* @starget: target to be checked
*/
void scsi_target_reap(struct scsi_target *starget)
{
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
- unsigned long flags;
- enum scsi_target_state state;
- int empty = 0;
-
- spin_lock_irqsave(shost->host_lock, flags);
- state = starget->state;
- if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
- empty = 1;
- starget->state = STARGET_DEL;
- }
- spin_unlock_irqrestore(shost->host_lock, flags);
-
- if (!empty)
- return;
-
- BUG_ON(state == STARGET_DEL);
- if (state == STARGET_CREATED)
+ BUG_ON(starget->state == STARGET_DEL);
+ if (starget->state == STARGET_CREATED)
scsi_target_destroy(starget);
else
- execute_in_process_context(scsi_target_reap_usercontext,
- &starget->ew);
+ scsi_target_reap_ref_put(starget);
}
/**
}
mutex_unlock(&shost->scan_mutex);
scsi_autopm_put_target(starget);
+ /*
+ * paired with scsi_alloc_target(). Target will be destroyed unless
+ * scsi_probe_and_add_lun made an underlying device visible
+ */
scsi_target_reap(starget);
put_device(&starget->dev);
out_reap:
scsi_autopm_put_target(starget);
- /* now determine if the target has any children at all
- * and if not, nuke it */
+ /*
+ * paired with scsi_alloc_target(): determine if the target has
+ * any children at all and if not, nuke it
+ */
scsi_target_reap(starget);
put_device(&starget->dev);
{
struct scsi_device *sdev;
struct device *parent;
- struct scsi_target *starget;
struct list_head *this, *tmp;
unsigned long flags;
sdev = container_of(work, struct scsi_device, ew.work);
parent = sdev->sdev_gendev.parent;
- starget = to_scsi_target(parent);
spin_lock_irqsave(sdev->host->host_lock, flags);
- starget->reap_ref++;
list_del(&sdev->siblings);
list_del(&sdev->same_target_siblings);
list_del(&sdev->starved_entry);
/* NULL queue means the device can't be used */
sdev->request_queue = NULL;
- scsi_target_reap(scsi_target(sdev));
-
kfree(sdev->inquiry);
kfree(sdev);
sdev->host->hostt->slave_destroy(sdev);
transport_destroy_device(dev);
+ /*
+ * Paired with the kref_get() in scsi_sysfs_initialize(). We have
+ * remoed sysfs visibility from the device, so make the target
+ * invisible if this was the last device underneath it.
+ */
+ scsi_target_reap(scsi_target(sdev));
+
put_device(dev);
}
continue;
if (starget->dev.parent == dev || &starget->dev == dev) {
/* assuming new targets arrive at the end */
- starget->reap_ref++;
+ kref_get(&starget->reap_ref);
spin_unlock_irqrestore(shost->host_lock, flags);
if (last)
scsi_target_reap(last);
list_add_tail(&sdev->same_target_siblings, &starget->devices);
list_add_tail(&sdev->siblings, &shost->__devices);
spin_unlock_irqrestore(shost->host_lock, flags);
+ /*
+ * device can now only be removed via __scsi_remove_device() so hold
+ * the target. Target will be held in CREATED state until something
+ * beneath it becomes visible (in which case it moves to RUNNING)
+ */
+ kref_get(&starget->reap_ref);
}
int scsi_is_sdev_device(const struct device *dev)
projects / GitHub / LineageOS / G12 / android_kernel_amlogic_linux-4.9.git / commitdiff