Dne 13. 07. 20 v 11:21 Martin Wilck napsal(a):
Hi Lixiaokeng,
@Zdenek, do we have to protect every libdm call, or is it sufficient
to protect only dm_task_run(), as lixiaokeng suggested?
Hi
It's actually hard to answer it in a simple way.
Several properties are held in library static variables. So converting libdm
into a fully threaded 'version' would basically require to duplicate all API
functions with extended 'context' structure passed in - where all buffers can
be maintained properly (and it's getting more complicated with signal handling
and debug logging).
ATM it doesn't look like there is a big need for threaded support of DM usage
as majority of tools spends most of their time outside thus 'serialization'
of lvm2 or dmeventd on libdm access look doesn't look like a big issue
(let's say there are far bigger fishes to hunt).
As for the issue of keeping control_fd open - there should be a synchronized
call of dm_hold_control_dev(0/1) - see the codebase of dmeventd.c in lvm2
code base - how we solve the control_fd handling.
Zdenek
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