Re: CVS commit: src/sys/opencrypto

[Paul Goyette <paul%whooppee.com@localhost>]

On Fri, 24 Jan 2014, Taylor R Campbell wrote:

> Shouldn't devsw_detach or config_fini_component handle this?  Why does
> the crypto device need special reference counting that other devices
> don't?

The crypto device isn't special in this regard.  Pretty much all device 
driver modules need this sort of ref-counting.  Without it, the race 
exists and at some future time something will have reused/overwritten 
the memory previously occupied by the module, with non-deterministic 
results.

Crypto is special only in that it tried to do some clean-up during the 
detach.  The pool_destroy() code correctly noticed that there were still 
some outstanding allocations that had not been returned.  So we sort of 
"got lucky" here and found out about the problem immediately, rather 
than waiting for some non-deterministic future.


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