From owner-freebsd-hackers@FreeBSD.ORG Sat Apr 1 18:35:36 2006 Return-Path: X-Original-To: hackers@freebsd.org Delivered-To: freebsd-hackers@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C9D6716A420 for ; Sat, 1 Apr 2006 18:35:36 +0000 (UTC) (envelope-from V.Haisman@sh.cvut.cz) Received: from service.sh.cvut.cz (service.sh.cvut.cz [147.32.127.214]) by mx1.FreeBSD.org (Postfix) with ESMTP id 39DD143D53 for ; Sat, 1 Apr 2006 18:35:33 +0000 (GMT) (envelope-from V.Haisman@sh.cvut.cz) Received: from localhost (localhost [127.0.0.1]) by service.sh.cvut.cz (Postfix) with ESMTP id 6167B1A330B; Sat, 1 Apr 2006 20:35:32 +0200 (CEST) Received: from service.sh.cvut.cz ([127.0.0.1]) by localhost (service [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 15298-10; Sat, 1 Apr 2006 20:35:27 +0200 (CEST) Received: from logout.sh.cvut.cz (logout.sh.cvut.cz [147.32.127.203]) by service.sh.cvut.cz (Postfix) with ESMTP id C0C3B1A3319; Sat, 1 Apr 2006 20:35:25 +0200 (CEST) Received: from [192.168.1.2] (localhost [127.0.0.1]) by logout.sh.cvut.cz (Postfix) with ESMTP id 7BD1F61C45; Sat, 1 Apr 2006 20:35:25 +0200 (CEST) Message-ID: <442EC7F7.3000608@sh.cvut.cz> Date: Sat, 01 Apr 2006 20:35:35 +0200 From: =?UTF-8?B?VsOhY2xhdiBIYWlzbWFu?= User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: Dan Nelson References: <442E9354.5010700@sh.cvut.cz> <20060401180311.GA83967@dan.emsphone.com> In-Reply-To: <20060401180311.GA83967@dan.emsphone.com> X-Enigmail-Version: 0.94.0.0 OpenPGP: id=733031B4 Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAMFBMVEUnMzWJm5S+0864pn5r blp/hnW2up7X7uqftbNRVUrW1LGBdGfHwJqPi3ScoYtBQzhDxGEwAAAAB3RJTUUH1QoQDDgyQtx8 HQAAAkNJREFUeJzFU0toU0EUPYu66CpGdCUUmoUJkpUDQUoNBVEUrBJsq1Ki2EIKIUZ8mydBhYi0 wVUXJVCLCrFN4DIEQdxIqdBIFsMkWD9YJClCRGKjJaviynjfe8RPogtXPcObuXPOPXd+PHj+Aeyo QNmobGLXVeANGM+GsP0B2yqHHNVoCD2LwLglVGZx7yXSlADR0uZu9C4Bpy3hUxPvH/cuUw6UoPCL h64I8KAJuMpwRU8uUMJy0OIpHVeXmulZoCc/t0LlTbJLEY1EudPRcnVjgAP5Osdl4K5HVP4+2bAI okaUA0Iq6Q59+Zy2eMWN6EpFTsa3+uD1+JKj4TPHuYTSMaLScLAaqk94YJqG4ds30hojOVgYoNJc NTztNU2TBYbhu9Aafnq08ORja37da1NwBrN/b7NVEc+b8yecuYkp08vNvLYneVZRaSH1vS0UnfHm OUPzWaZufHPmCWSdWrfeGVQQKmcsO4If8pAdXJ/xF4QQAeOVY1AQQcfirwkLUWeWVTgi6vaGt2xe BGzBEIMQorru8RxgPqY1V6uxYnwVBRZEI1ytCm3dE8mC2DgcbzCJGHdBEVDKuWDSwsrSGoqzJmNt 2jJpNueIH0qS8/0JrDKnVBdvOzIsdVr4zaX9dn9xcLLKdCtQGfutVacLE9Ja+yfbDvO4aMWrklfK /JYv15C8Kw9S10kup5Bys0N1bLdcn4HvTl/Xlh6Fpllwj5/XpH9BUXn/ym0Dvv7Rt2MywojpYiSi i7Hsscaa19zZ//y/hR+BT/ns80nmJAAAAABJRU5ErkJggg== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig42E91DB545B863081B0E1FE1" X-Virus-Scanned: by amavisd-new at sh.cvut.cz X-Spam-Status: No, hits=-5.9 tagged_above=-255.0 required=5.0 tests=ALL_TRUSTED, BAYES_00 X-Spam-Level: Cc: hackers@freebsd.org Subject: Re: kqueue oddity X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 01 Apr 2006 18:35:36 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig42E91DB545B863081B0E1FE1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Dan Nelson wrote: > In the last episode (Apr 01), Vclav Haisman said: >> Hi, >> I have a little problem with kqueue/kevent. I am getting somewhat >> strange events from kevent(). The struct kevent's contents looks like = this: >> >> kevent {.ident =3D 1, .filter =3D 0xfffffffe, .flags =3D 0x0001,=20 >> .fflags =3D 0x00000000, .data =3D 0x000084c6} >> >> .ident =3D=3D 1 is stdout. >> .filter =3D=3D 0x fffffffe is -2 is EVFILT_WRITE which makes sense for= stdout. >> .fflags is empty, nothing out of ordinary for EVFILT_WRITE. >> And here comes the oddity: .flags =3D=3D 0x0001 means EV_ADD which tot= ally >> doesn't make sense to me and neither does according to man kqueue. The= >> code that exhibits this behaviour is io_loop_handler_run() in >> ioloop-kqueue.c of Dovecot IMAP server. >=20 > It's a kqueue bug, but a minor one. The problem is that the same > "flags" field is used to pass "actions" from the client, and return > status from the kernel. When you call kqueue with EV_ADD, the kernel > never clears the flags when creating the internal object, so it's > always visible when events fire. This can get annoying when trussing > kqueue-using programs because very single event has the EV_ADD flag :) > Apply the following diff to have the kernel strip EV_ADD: > =20 > Index: kern_event.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > RCS file: /home/ncvs/src/sys/kern/kern_event.c,v > retrieving revision 1.79.2.9 > diff -u -p -r1.79.2.9 kern_event.c > --- kern_event.c 29 Jun 2005 18:08:31 -0000 1.79.2.9 > +++ kern_event.c 7 Jul 2005 18:51:29 -0000 > @@ -864,6 +864,7 @@ findkn: > kev->fflags =3D 0; > kev->data =3D 0; > kn->kn_kevent =3D *kev; > + kn->kn_kevent.flags &=3D ~EV_ADD;=20 > kn->kn_status =3D KN_INFLUX|KN_DETACHED; > =20 > error =3D knote_attach(kn, kq); >=20 >=20 Thanks. Why isn't this fix applied? From the patch's time stamp it seems like it is known for quite some time now. 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