Date: Sat, 14 May 2016 13:10:44 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Jilles Tjoelker <jilles@stack.nl> Cc: threads@freebsd.org, arch@freebsd.org Subject: Re: Robust mutexes implementation Message-ID: <20160514101044.GM89104@kib.kiev.ua> In-Reply-To: <20160513223434.GA47987@stack.nl> References: <20160505131029.GE2422@kib.kiev.ua> <20160506233011.GA99994@stack.nl> <20160507165956.GC89104@kib.kiev.ua> <20160508125222.GA48862@stack.nl> <20160509025107.GN89104@kib.kiev.ua> <20160513153716.GA30576@stack.nl> <20160513201916.GF89104@kib.kiev.ua> <20160513223434.GA47987@stack.nl>
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On Sat, May 14, 2016 at 12:34:34AM +0200, Jilles Tjoelker wrote: > On Fri, May 13, 2016 at 11:19:16PM +0300, Konstantin Belousov wrote: > > BTW, is there a chance of Austin Group get notified of, and possibly > > adopting, MAP_EXCL flag ? > > You could send a message to the mailing list. MAP_EXCL is not used in > the FreeBSD base but Debian code search shows Chromium and Hurd ftpfs > mentioning it in comments. It is not clear if they reference FreeBSD flag, or just come to this semi-obvious idea independently. Anway, it is not used because feature is not present anywhere (except us). I do not want to present this on ag list as a stranger with bad language. > I don't trust the if (umtx_shm_vnobj_persistent) in > sys/vm/vnode_pager.c: > > + if (umtx_shm_vnobj_persistent) > + umtx_shm_object_terminated(obj); > > If umtx_shm_vnobj_persistent is turned off via sysctl between the check > in sys/vm/vm_object.c and this one, don't we have a leak? Removed the test in the vnode_destroy_vobject(), doing the umtx termination unconditionally on reclaim. > > 'Reviewed by: jilles' is fine otherwise. Updated patch is at https://www.kib.kiev.ua/kib/pshared/robust.5.patch P.S. I will document UMUTEX_ROBUST/UMUTEX_RB_* and UMTX_OP_ROBUST_LISTS after the feature is committed.
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