Date: Tue, 29 Aug 2006 17:15:54 +0200 From: Andre Oppermann <andre@freebsd.org> To: Randall Stewart <rrs@cisco.com>, freebsd-net@freebsd.org, andre@FreeBSD.org Subject: Re: Problem with uipc_mbuf.c Message-ID: <44F45A2A.8030405@freebsd.org> In-Reply-To: <20060828224452.GK37035@funkthat.com> References: <44F35A65.3080605@cisco.com> <20060828224452.GK37035@funkthat.com>
next in thread | previous in thread | raw e-mail | index | archive | help
John-Mark Gurney wrote: > Randall Stewart wrote this message on Mon, Aug 28, 2006 at 17:04 -0400: >> atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 0) { > ^ > > This should be 1 not 0.. as apparently fetchadd_int returns the old value > (at least that's what atomic(9) says), which means that if we ever race > on this comparision, we won't free though we should of... > > if we look at refcount.h, it does: > return (atomic_fetchadd_int(count, -1) == 1); > > which release a reference and apparently returns true if it needs to > be free'd... > > Though the wierd part is that andre, "fixed" it to be 0 in 1.157: > Fix a logic error introduced with mandatory mbuf cluster refcounting and > freeing of mbufs+clusters back to the packet zone. Honestly I'm a bit confused myself now and have to dig up things from when I did the change. However I'm certain there was a problem and the commit fixed it in some way (not necessarily the correct way). Before the 'fix' there were some larger leaks going on. -- Andre
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?44F45A2A.8030405>