Re: [Xen-devel] [PATCH v2 3/6] libxc/migration: Be rather stricter with illformed callers

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 11/05/15 12:33, Ian Campbell wrote:
> On Fri, 2015-05-08 at 22:14 +0100, Andrew Cooper wrote:
>> The migration code itself should be able to validly assume all mandatory
>> callbacks are set up.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
>> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
>> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
>> CC: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
>> ---
>>  tools/libxc/xc_sr_save.c         |    4 ++++
>>  tools/libxc/xc_sr_save_x86_hvm.c |    7 -------
>>  2 files changed, 4 insertions(+), 7 deletions(-)
>>
>> diff --git a/tools/libxc/xc_sr_save.c b/tools/libxc/xc_sr_save.c
>> index 5d9c267..83f0591 100644
>> --- a/tools/libxc/xc_sr_save.c
>> +++ b/tools/libxc/xc_sr_save.c
>> @@ -738,6 +738,10 @@ int xc_domain_save2(xc_interface *xch, int io_fd, 
>> uint32_t dom,
>>      ctx.save.max_iterations = 5;
>>      ctx.save.dirty_threshold = 50;
>>  
>> +    /* Sanity checks for callbacks. */
>> +    if ( hvm )
>> +        assert(callbacks->switch_qemu_logdirty);
> assert(!hvm || callbacks->switch_qemu_logdirty)
>
> ?

I would argue that the former is far easier to read.

The intention for this, and a subsequent patch, is "if (some option)
assert(mandatory callbacks for option)"

~Andrew

>
>> +
>>      IPRINTF("In experimental %s", __func__);
>>      DPRINTF("fd %d, dom %u, max_iters %u, max_factor %u, flags %u, hvm %d",
>>              io_fd, dom, max_iters, max_factor, flags, hvm);
>> diff --git a/tools/libxc/xc_sr_save_x86_hvm.c 
>> b/tools/libxc/xc_sr_save_x86_hvm.c
>> index 8baa104..58efdb9 100644
>> --- a/tools/libxc/xc_sr_save_x86_hvm.c
>> +++ b/tools/libxc/xc_sr_save_x86_hvm.c
>> @@ -166,13 +166,6 @@ static int x86_hvm_setup(struct xc_sr_context *ctx)
>>  {
>>      xc_interface *xch = ctx->xch;
>>  
>> -    if ( !ctx->save.callbacks->switch_qemu_logdirty )
>> -    {
>> -        ERROR("No switch_qemu_logdirty callback provided");
>> -        errno = EINVAL;
>> -        return -1;
>> -    }
>> -
>>      if ( ctx->save.callbacks->switch_qemu_logdirty(
>>               ctx->domid, 1, ctx->save.callbacks->data) )
>>      {
>


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