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From: John Baldwin <jhb@freebsd.org>
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Cc: mdf@freebsd.org
Subject: Re: uma_zfree(NULL) is broken
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On Monday, October 18, 2010 4:59:17 pm mdf@freebsd.org wrote:
> There's explicit protection for free(NULL, M_FOO), but uma_zfree(zone,
> NULL) will put NULL in the local bucket and then probably return it
> later from a uma_zalloc call.  Obviously it's not a good idea to call
> uma_zfree(9) on NULL, but in this case it's an easy mistake to make
> when e.g. converting a set of malloc(9)/free(9) uses into uma(9).
> 
> So is the "right" thing to allow a uma_zfree(NULL) and silently
> succeed, like for free(9)?  That would be my guess, but I'm open to
> alternatives.

Given that free(3) and free(9) both handle NULL, I think it makes sense for 
uma_zfree() to do so as well.

-- 
John Baldwin