[PATCH v3 2/2] nvme: fix cdev lifetime

[John Garry]

On 17/07/2026 08:10, Nilay Shroff wrote:
>> nvme_ns_chr_open() and nvme_ns_chr_release() call nvme_ns_open() and nvme_ns_relase(), respectively, and they do more than get and put a ref to the NS - specifically they also check that they are not called for multipath mode (as the NS bdev/cdev should be hidden) and take/put a reference to the controller ops module. Why are those addition actions not required for the cdev? Or should it be done when we add/del the cdev (like in this patch)?
>> 
> 
> I think the first check in nvme_ns_open() that verifies we have not entered
> while multipath is enabled is essentially a sanity/paranoia check.
 >

And just a nvme_ns_chr_open() version which does this check has no value.

> As for the module reference, I think that is redundant for the cdev path.
> chrdev_open() already takes a reference to module before invoking
> nvme_ns_chr_open(), so IMO, nvme_ns_open() taking another reference to
> module appears unnecessary for this path.
> 
> Unless I'm missing something, it seems nvme_ns_chr_open()/nvme_ns_chr_release()
> don't provide any additional lifetime guarantees for the cdev beyond what is
> already handled elsewhere.

Yeah, it seems that way.