Re: [PATCH] Fix reference counting for failed SCSI devices

James Bottomley
2005-05-24T22:58:12Z

On Tue, 2005-05-24 at 11:38 +0200, Hannes Reinecke wrote:
> whenever the scsi-ml tries to scan non-existent devices the reference
> count in scsi_alloc_sdev() and scsi_probe_and_add_lun() is not adjusted
> properly. Every call to XXX_initialize in the driver core sets the
> reference count to 1, so for a proper deallocation an explicit XXX_put()
> has to be done.

That's true, but I don't see what the problem is if the device has never
been made visible.

> + put_device(&starget->dev);

this would amount to a double put, since the parent put method is called
in the device release.

> + class_device_put(&sdev->sdev_classdev);

This is unnecessary since the class device is simply occupying a private
area in the scsi_device. As long as its never made visible to the
system, its refcount is irrelevant

> put_device(&sdev->sdev_gendev);
> out:
> if (display_failure_msg)
> @@ -855,6 +857,8 @@ static int scsi_probe_and_add_lun(struct
> if (sdev->host->hostt->slave_destroy)
> sdev->host->hostt->slave_destroy(sdev);
> transport_destroy_device(&sdev->sdev_gendev);
> + class_device_put(&sdev->sdev_classdev);
> + put_device(sdev->sdev_gendev.parent);

same should apply here. As long as this cascade occurs before
scsi_add_lun() (which calls scsi_sysfs_add_sdev()), which is what makes
the whole set of devices and classes visible.

James