Date: Wed, 8 Oct 2003 11:15:18 +0100 From: Bruce M Simpson <bms@spc.org> To: Pawel Jakub Dawidek <nick@garage.freebsd.pl> Cc: hsu@freebsd.org Subject: Re: Dynamic reads without locking. Message-ID: <20031008101518.GH6524@saboteur.dek.spc.org> In-Reply-To: <20031008101222.GB520@garage.freebsd.pl> References: <20031008083059.GA520@garage.freebsd.pl> <20031008114506.I63940@beagle.fokus.fraunhofer.de> <20031008101222.GB520@garage.freebsd.pl>
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--ikeVEW9yuYc//A+q Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Oct 08, 2003 at 12:12:22PM +0200, Pawel Jakub Dawidek wrote: > But I'm not talking about non-atomic reads. What I'm want to show is that > even atomic read (without lock) is dangerous in some cases. >=20 > +> If you don't care about occasionally reading false data (for statistic= s or > +> such stuff) you can go without the lock. >=20 > I'm afraid that many developers thinks that atomic reads are always safe > without locks (there are many such reads in sources). I hope I'm wrong. Correcto. A while back peter@ and I discussed this. If you can think of such places, share what you've found, and let's discuss fixing the offending code so as to avoid nasty races. BMS --ikeVEW9yuYc//A+q Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Comment: '' iD8DBQE/g+O1ueUpAYYNtTsRAgdDAJ94v8Xv46lNm5eUGrcn+XUO5RHTBgCgh5iR N7yUSOR1WKgbHq2oltOJH2w= =RJcJ -----END PGP SIGNATURE----- --ikeVEW9yuYc//A+q--
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