Re: [PATCH] netlink: Allow command handler to use l_netlink_cancel

[Denis Kenzior <denkenz@gmail.com>]

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Hi Andrew,

>>> Would it not be better to simply remove the command from the command_lookup
>>> hashmap prior to dispatch, and have l_netlink_cancel simply fail?
>>
>> Yes, that would work.
> 
> On a second thought, I think it's better the other way.  The
> l_netlink_cancel() call can be used as a request to forget the
> callbacks.  The user may be tearing down the object they passed as
> user_data for example.  IIRC we did take that use case into
> consideration in some of the other APIs, what do you think?

Which other way?  Ahhh, I think I get it... You want to unset the destroy 
callback or prevent it from being called subsequently when inside the handler by 
issuing l_netlink_cancel?

I actually don't think any ell APIs work this way.  l_dbus for example simply 
removes the pending request prior to dispatch (which is what I suggested 
earlier).  Hence l_dbus_cancel wouldn't work on it inside the l_dbus_send callback.

Even APIs that use the watchlist pattern don't do it this way.  You may be 
thinking of the scan API inside iwd, which did it for a different reason.

Regards,
-Denis