Suricata

The attached patch implement a similar idea. It adds a data release mechanism. If the capture module has a call to indicate that userland has finished with the data,
it is possible to use this system. The data will then be released when the treatment of the packet is finished.

To do so the Packet structure has been modified:

+    TmEcode (*ReleaseData)(struct Packet_ *);
+    void *relptr;

If ReleaseData and relptr are not null, the function is called
when the treatment of the Packet is finished.

Thus it is sufficient for the capture module to code a function
wrapping the data release mechanism and to assign it to ReleaseData
field.

All locking have to be handled by the ReleaseData function.

Merged https://github.com/regit/suricata/commit/8fecd95a6750977872ab3ebc5ddbe926da61c302

Thanks Eric!