Date: Sat, 24 Nov 2007 19:09:22 +0100 From: "Attilio Rao" <attilio@freebsd.org> To: "Robert Watson" <rwatson@freebsd.org> Cc: Stephan Uphoff <ups@freebsd.org>, Max Laier <max@love2party.net>, Alfred Perlstein <alfred@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: rwlocks, correctness over speed. Message-ID: <3bbf2fe10711241009g126e8bd1ldca2468e7956c902@mail.gmail.com> In-Reply-To: <20071124162322.V14018@fledge.watson.org> References: <20071121222319.GX44563@elvis.mu.org> <20071123082339.GN44563@elvis.mu.org> <47469328.8020404@freebsd.org> <20071123092415.GP44563@elvis.mu.org> <4746F858.4070301@freebsd.org> <20071123235346.E14018@fledge.watson.org> <3bbf2fe10711231930m459dc800wbbb894b9fd50ca13@mail.gmail.com> <20071124103231.A14018@fledge.watson.org> <3bbf2fe10711240553k1eb35a5au23cae8af08f5864c@mail.gmail.com> <20071124162322.V14018@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
2007/11/24, Robert Watson <rwatson@freebsd.org>: > On Sat, 24 Nov 2007, Attilio Rao wrote: > > >> I must have missed recursion arriving then -- I'll modify uipc_usrreq.c to > >> set the recursion flag on the rwlock in UNIX domain sockets rather than > >> doing the nasty hack that was previously required. At the time, the hack > >> was added because it seemed recursion was not going to be added to rwlocks, > >> but sonewconn() behavior for listen sockets really ended up requiring it. > > > > attilio 2007-06-26 21:31:56 UTC > > > > FreeBSD src repository > > > > Modified files: > > sys/kern kern_rwlock.c > > sys/sys _rwlock.h rwlock.h > > Log: > > Introduce a new rwlocks initialization function: rw_init_flags. > > This is very similar to sx_init_flags: it initializes the rwlock using > > special flags passed as third argument (RW_DUPOK, RW_NOPROFILE, > > RW_NOWITNESS, RW_QUIET, RW_RECURSE). > > Among these, the most important new feature is probabilly that rwlocks > > can be acquired recursively now (for both shared and exclusive paths). > > Yes, that was four months after I added rw_wowned(9) to work around the lack > of recursion support. :-) However, it looks like the man page was never > updated? It contains the following rather explicit language: > > Another important property is that shared holders of rwlock can recurse, > but exclusive locks are not allowed to recurse. Yes, I'm going to fix the manpage ASAP. Thanks, for the report. Attilio -- Peace can only be achieved by understanding - A. Einstein
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3bbf2fe10711241009g126e8bd1ldca2468e7956c902>