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

[James Bottomley <James.Bottomley@SteelEye.com>]

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


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