Re: [Qemu-devel] [PATCH 2/6] block: Acquire the AioContext in scsi_*_realize()

[Alberto Garcia]

On Fri 11 Jan 2019 04:02:13 PM CET, Kevin Wolf wrote:
>> @@ -2568,7 +2579,10 @@ static void scsi_block_realize(SCSIDevice *dev, Error 
>> **errp)
>>      }
>>  
>>      /* check we are using a driver managing SG_IO (version 3 and after) */
>> +    ctx = blk_get_aio_context(s->qdev.conf.blk);
>> +    aio_context_acquire(ctx);
>>      rc = blk_ioctl(s->qdev.conf.blk, SG_GET_VERSION_NUM, &sg_version);
>> +    aio_context_release(ctx);
>>      if (rc < 0) {
>>          error_setg_errno(errp, -rc, "cannot get SG_IO version number");
>>          if (rc != -EPERM) {
>
> This is probably not enough. get_device_type() and
> scsi_generic_read_device_inquiry() below issue more ioctls (but we
> need to be careful not to include the scsi_realize() call in the
> locked section if you take the lock again there).

Hmmm, another alternative is not to take the lock in scsi_realize() and
take it instead in all the functions that call it (it's 4 or 5).

Berto