RE: [PATCH] scsi: smartpqi_init: Reporting 'logical unit failure'

[Elliott, Robert (Persistent Memory)]

> -----Original Message-----
> From: linux-kernel-ow...@vger.kernel.org 
> [mailto:linux-kernel-ow...@vger.kernel.org] On Behalf Of
> Erwan Velu
> Sent: Wednesday, February 27, 2019 10:32 AM
> Subject: [PATCH] scsi: smartpqi_init: Reporting 'logical unit failure'
> 
> When this HARDWARE_ERROR/0x3e/0x1 case is triggered, the logical volume is 
> offlined.
> When reading the kernel log, the cause why the device got offlined isn't 
> reported to the user.
> This situation makes difficult for admins to estimate _why_ the volume got 
> offlined.
> Reading this part of the code makes clear this is because driver received a 
> HARDWARE_ERROR/0x3e/0x1
> which is a 'logical unit failure'.
> 
> This patch is just about reporting that fact to help admins making a 
> relationship between this event
> and the offlining.
> 
> Signed-off-by: Erwan Velu <e.v...@criteo.com>
> ---
>  drivers/scsi/smartpqi/smartpqi_init.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c 
> b/drivers/scsi/smartpqi/smartpqi_init.c
> index f564af8949e8..89f37d76735c 100644
> --- a/drivers/scsi/smartpqi/smartpqi_init.c
> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
> @@ -2764,6 +2764,12 @@ static void pqi_process_raid_io_error(struct 
> pqi_io_request *io_request)
>                               sshdr.sense_key == HARDWARE_ERROR &&
>                               sshdr.asc == 0x3e &&
>                               sshdr.ascq == 0x1) {
> +                     struct pqi_ctrl_info *ctrl_info = 
> shost_to_hba(scmd->device->host);
> +                     struct pqi_scsi_dev *device = scmd->device->hostdata;
> +
> +                     dev_err(&ctrl_info->pci_dev->dev, "received 'logical 
> unit failure' from controller
> for scsi %d:%d:%d:%d\n",
> +                                                     
> ctrl_info->scsi_host->host_no, device->bus,
> +                                                     device->target, 
> device->lun);
>                       pqi_take_device_offline(scmd->device, "RAID");
>                       host_byte = DID_NO_CONNECT;
>               }

Be careful printing errors per-IO; you could get thousands of them if things go 
bad.
The block layer print_req_error() uses printk_ratelimited(KERN_ERR) for that 
reason,
and the SCSI layer scsi_io_completion_action() maintains a ratelimit on its own.

The dev_err_ratelimited() macro might be a good fit here.


---
Robert Elliott, HPE Persistent Memory