Re: [PATCH 05/29] ibmvfc: alloc/dealloc sub-queues for nvme channels

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Failure to register NVMe sub-queues silently disables SCSI multiqueue support due to a shared state flag.
--

commit 6eb0f2ef7c51067f6c97ea8c13211afa2e19dcc4
Author: Tyrel Datwyler <tyreld@linux.ibm.com>

ibmvfc: alloc/dealloc sub-queues for nvme channels

This patch allocates, registers, deregisters, and releases NVMe subordinate
CRQs alongside the existing SCSI sub-CRQs. It integrates the NVMe queue
lifecycle with the existing SCSI queue lifecycle to ensure both protocols
are reset consistently.

> diff --git a/drivers/scsi/ibmvscsi/ibmvfc-core.c b/drivers/scsi/ibmvscsi/ibmvfc-core.c
> index 5732ccf2ac1c0..6f5e8b3cbfc82 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc-core.c
> +++ b/drivers/scsi/ibmvscsi/ibmvfc-core.c

[ ... ]

> @@ -6109,6 +6113,13 @@ static void ibmvfc_init_sub_crqs(struct ibmvfc_host *vhost)
>  
>  	ibmvfc_reg_sub_crqs(vhost, &vhost->scsi_scrqs);
>  
> +	if (vhost->nvme_enabled) {
> +		if (ibmvfc_alloc_channels(vhost, &vhost->nvme_scrqs))
> +			vhost->nvme_enabled = 0;
> +		else
> +			ibmvfc_reg_sub_crqs(vhost, &vhost->nvme_scrqs);

[Severity: High]
Does a failure to register NVMe sub-queues unintentionally disable SCSI
multiqueue support here?

If ibmvfc_reg_sub_crqs() fails while registering the NVMe channels, it handles
the error by unregistering the partial channels and setting a shared host flag:

ibmvfc_reg_sub_crqs() {
    ...
    if (ibmvfc_register_channel(vhost, channels, i)) {
        for (j = i; j > 0; j--)
            ...
        vhost->do_enquiry = 0;
        return;
    }
}

Since ibmvfc_reg_sub_crqs() is now called for NVMe right after successfully
registering the SCSI sub-queues, setting vhost->do_enquiry to 0 upon an NVMe
registration failure will cause the driver to skip channel enquiry during the
NPIV login sequence. 

Will this cause the successfully registered SCSI channels to be silently
ignored if the hypervisor rejects the NVMe sub-crqs allocation?

> +	}
> +
>  	LEAVE;
>  }
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260623013035.3436640-1-tyreld@linux.ibm.com?part=5