[Qemu-devel] Re: [PATCH 14/15] megasas: LSI Megaraid SAS emulation

[Hannes Reinecke <hare@suse.de>]

On 11/25/2010 03:36 PM, Stefan Hajnoczi wrote:
> On Wed, Nov 24, 2010 at 11:16 AM, Hannes Reinecke <hare@suse.de> wrote:
>> +static int megasas_pd_get_info_submit(SCSIDevice * sdev, int lun,
>> +                                      struct megasas_cmd_t *cmd)
>> +{
>> +    struct mfi_pd_info * info = cmd->iov_buf;
>> +    uint8_t cmdbuf[6];
>> +    SCSIRequest *req;
>> +
>> +    if (info->inquiry_data[4] == 0) {
>> +        /* Additional length is zero, resubmit */
>> +        megasas_setup_inquiry(cmdbuf, 0, info->inquiry_data,
>> +                              sizeof(info->inquiry_data));
>> +        req = sdev->info->alloc_req(sdev, (uint32_t) -1, lun);
>> +        if (!req) {
>> +            return MFI_STAT_FLASH_ALLOC_FAIL;
>> +        }
>> +        DPRINTF_DCMD("PD get info submit std inquiry to dev %d\n", lun);
>> +        req->hba_private = cmd;
>> +        if (cmd->sdev->info->send_command(req, cmdbuf) > 0)
>> +            cmd->sdev->info->read_data(req);
>> +        return MFI_STAT_INVALID_STATUS;
> 
> Here...
> 
>> +    } else if (info->vpd_page83[3] == 0) {
>> +        /* Additional length is zero, resubmit */
>> +        megasas_setup_inquiry(cmdbuf, 0x83,(uint8_t *)info->vpd_page83,
>> +                              sizeof(info->vpd_page83));
>> +        req = sdev->info->alloc_req(sdev, (uint32_t) -1, lun);
>> +        if (!req) {
>> +            return MFI_STAT_FLASH_ALLOC_FAIL;
>> +        }
>> +        DPRINTF_DCMD("PD get info submit vpd inquiry to dev %d\n", lun);
>> +        req->hba_private = cmd;
>> +        if (cmd->sdev->info->send_command(req, cmdbuf) > 0)
>> +            cmd->sdev->info->read_data(req);
>> +        return MFI_STAT_INVALID_STATUS;
> 
> ...and here I can't tell for sure if an error status is returned
> intentionally or whether this is an if statement without {}-related
> bug.
> 
> On one hand it looks like it could be intentional.  On the other hand
> we went through the trouble of sending an inquiry command that may
> have succeeded but we're still returning an error status.
> 

MFI_STAT_INVALID_STATUS is _not_ an error status. It's used
internally to signal that a command is still being processed.
->read_data() itself doesn't have a meaningful return code;
we need to wait for the ->complete callback to get results.
So we're returning MFI_STAT_INVALID_STATUS to signal this condition.

So that's ok.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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