[PATCH] scsi/ibmvscsi: /sys/class/scsi_host/hostX/config doesn't show any information

[Robert Jennings]

On Sun, Jul 29, 2012 at 8:33 PM, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> n Wed, 2012-07-18 at 18:49 +0200, olaf at aepfle.de wrote:
>> From: Linda Xie <lxiep at us.ibm.com>
>>
>> Expected result:
>> It should show something like this:
>> x1521p4:~ # cat /sys/class/scsi_host/host1/config
>> PARTITIONNAME='x1521p4'
>> NWSDNAME='X1521P4'
>> HOSTNAME='X1521P4'
>> DOMAINNAME='RCHLAND.IBM.COM'
>> NAMESERVERS='9.10.244.100 9.10.244.200'
>>
>> Actual result:
>> x1521p4:~ # cat /sys/class/scsi_host/host0/config
>> x1521p4:~ #
>>
>> This patch changes the size of the buffer used for transfering config
>> data to 4K. It was tested against 2.6.19-rc2 tree.
>>
>> Reported by IBM during SLES11 beta testing:
>
> So this patch just seems to blindly replace all occurrences of PAGE_SIZE
> with HOST_PAGE_SIZE which is utterly wrong. Only one of those needs to
> be changed, the one passed to ibmvscsi_do_host_config() which is what's
> visible to the server, all the rest is just sysfs attributes and should
> remain as-is.
>
> Additionally (not even mentioning that there is no explanation as to
> what the real problem is anywhere in the changeset) I don't like the
> fix. The root of the problem is that the MAD header has a 16-bit length
> field, so writing 0x10000 (64K PAGE_SIZE) into it doesn't quite work.
>
> So in addition to a better comment, I would suggest a fix more like
> this:
>
> scsi/ibmvscsi: Fix host config length field overflow
>
> The length field in the host config packet is only 16-bit long, so
> passing it 0x10000 (64K which is our standard PAGE_SIZE) doesn't
> work and result in an empty config from the server.
>
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> CC: <stable at vger.kernel.org>

Acked-by: Robert Jennings <rcj at linux.vnet.ibm.com>

Tested with an IBM i host and confirmed the fix.

> ---
>
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 3a6c474..337e8b3 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -1541,6 +1541,9 @@ static int ibmvscsi_do_host_config(struct ibmvscsi_host_data *hostdata,
>
>         host_config = &evt_struct->iu.mad.host_config;
>
> +       /* The transport length field is only 16-bit */
> +       length = min(0xffff, length);
> +
>         /* Set up a lun reset SRP command */
>         memset(host_config, 0x00, sizeof(*host_config));
>         host_config->common.type = VIOSRP_HOST_CONFIG_TYPE;
>
>
> --
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