Re: [Qemu-devel] [PATCH 3/4] 9pfs: stat_to_qid: use device as input to qid.path

[Antonios Motakis <antonios.motakis@huawei.com>]

On 02/09/2018 10:58 PM, Emilio G. Cota wrote:
> On Fri, Feb 09, 2018 at 16:13:26 +0100, Greg Kurz wrote:
>> On Thu, 8 Feb 2018 19:00:18 +0100
>> <antonios.motakis@huawei.com> wrote:
> (snip)
>>> +/* creative abuse of tb_hash_func7, which is based on xxhash */
>>> +static uint32_t qpp_hash(QppEntry e)
>>> +{
>>> +    return tb_hash_func7(e.ino_prefix, e.dev, 0, 0, 0);
>> Hmm... Looking at git log include/exec/tb-hash-xx.h, I see that this hash
>> function signature evolved according to TCG needs. It started with 3
>> arguments, then 4 and we have 5 today.
>>
>> So I don't think we should add another unrelated user. Probably best to
>> have our own version. Also it seems it could be simpler since you always
>> pass 0 for the third and later arguments.
> It's fine to use it; the compiler will do the right thing
> with those '0' arguments, because the function is always inlined.
>
> That said, I have some cleanup patches to export this as xxhash and make
> tb_hash a user of it. The patches also remove most of the ugly 0's from
> callers. Those patches will have to wait for a bit though, so for now
> just use tb_hash_func7.

I guess this is why it's a good idea to share patches even if still rough ;)
So I will not worry about this part for now.

>
> (snip)
>>> +        val = g_malloc0(sizeof(QppEntry));
>>> +        if (!val) {
>>> +            return -ENOMEM;
>>> +        }
> g_malloc0 and all other glib memory allocation functions only
> return NULL if the size argument is 0.
> If out of memory, the application is terminated, which is why
> this check is not needed.
> Reference:
>    https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html#glib-Memory-Allocation.description

Thanks for the clarification.

>
> Thanks,
>
> 		Emilio