How Fiasco reclaim task resources when the task exits (abnormally) ?

BogDan bog_dan_ro at
Mon Jun 10 11:44:50 CEST 2013


>>  What happens with a task resources when a task crashes or it leaks

>>  resources at exit?
>>  How this resources (e.g. memory, file descriptors, any other
>>  capabilities) are reclaimed  back by the o.s. ? 
> FDs and caps are local to the task, so just memory.

Hmm it must be a misunderstanding here, it can't be  just memory 
because IMHO also FDs can't be local ... I can't image how they can
be managed locally ... 
Let me give two (very similar) examples to be more clear:
- when I open a file (exclusive mode) a VFS has to do something to 
prevent other FDs to read/write into that file, so it creates and
keeps a thing (FD, capability) inside it until the application close the 
FD. Now the problem comes when the application exits (it crashes)
without closing the FD, is there any way to notify the VFS server
about it?

- when I create a socket and listen on a port, other apps can't
listen on the same port, meaning that there is another server which
manage this resource. Like in the previous example I don't want to
reboot my os to use that port after the application crashed :)
> Providers need to

> check whether there are any further users of their resource and if not
> they can free it (the kernel provides support for doing so).

The providers need to check or they are notified by the kernel when a
resources is not referenced by anyone? I'm very interested in this topic,
is there any example that I can check?



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