From owner-svn-src-projects@FreeBSD.ORG Mon Jul 30 15:53:25 2012 Return-Path: Delivered-To: svn-src-projects@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 73E1C106566B; Mon, 30 Jul 2012 15:53:25 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 0C8748FC18; Mon, 30 Jul 2012 15:53:24 +0000 (UTC) Received: from skuns.kiev.zoral.com.ua (localhost [127.0.0.1]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id q6UF03xU049131; Mon, 30 Jul 2012 18:00:06 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5) with ESMTP id q6UExC1l080550; Mon, 30 Jul 2012 17:59:12 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5/Submit) id q6UExCbd080549; Mon, 30 Jul 2012 17:59:12 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 30 Jul 2012 17:59:12 +0300 From: Konstantin Belousov To: Attilio Rao Message-ID: <20120730145912.GZ2676@deviant.kiev.zoral.com.ua> References: <201207301350.q6UDobCI099069@svn.freebsd.org> <20120730143943.GY2676@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="zUahwhnDqgGY+q9P" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.0 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: Davide Italiano , svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r238907 - projects/calloutng/sys/kern X-BeenThere: svn-src-projects@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the src " projects" tree" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Jul 2012 15:53:25 -0000 --zUahwhnDqgGY+q9P Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 30, 2012 at 03:51:22PM +0100, Attilio Rao wrote: > On 7/30/12, Konstantin Belousov wrote: > > On Mon, Jul 30, 2012 at 03:24:26PM +0100, Attilio Rao wrote: > >> On 7/30/12, Davide Italiano wrote: > >> > On Mon, Jul 30, 2012 at 4:02 PM, Attilio Rao > >> > wrote: > >> > Thanks for the comment, Attilio. > >> > Yes, it's exactly what you thought. If direct flag is equal to one > >> > you're sure you're processing a callout which runs directly from > >> > hardware interrupt context. In this case, the running thread cannot > >> > sleep and it's likely you have TDP_NOSLEEPING flags set, failing the > >> > KASSERT() in THREAD_NO_SLEEPING() and leading to panic if kernel is > >> > compiled with INVARIANTS. > >> > In case you're running from SWI context (direct equals to zero) code > >> > remains the same as before. > >> > I think what I'm doing works due the assumption thread running never > >> > sleeps. Do you suggest some other way to handle this? > >> > >> Possibly the quicker way to do this is to have a way to deal with the > >> TDP_NOSLEEPING flag in recursed way, thus implement the same logic as > >> VFS_LOCK_GIANT() does, for example. > >> You will need to change the few callers of THREAD_NO_SLEEPING(), but > >> the patch should be no longer than 10/15 lines. > > > > There are already curthread_pflags_set/restore KPI designed exactly to > > handle > > nested private thread flags. >=20 > Yes, however I would use curthread_pflags* KPI within > THREAD_NO_SLEEPING() as this name is much more explicit. >=20 Sure, hiding it in THREAD_NO_SLEEPING (THREAD_NO_SLEEP_ENTER/LEAVE ?) is the way to use curthread_pflags_set there. As a second though, on the other hand, is it safe to modify td_flags from the interrupt context at all ? Probably yes if interrupt handler always leave td_pflags in the same state on leave as it was on entry, but couldn't too smart compiler cause inconsistent view of td_pflags inside the handler ? > > Also, I wonder, should you assert somehow that direct dispatch cannot b= lock > > as well ? >=20 > Yes, it would be optimal, but I don't think we have a flag for that > right now, do we? I am not aware of such flag, this might be a good reason to introduce it, if issue about td_pflags is just a product of my imagination. --zUahwhnDqgGY+q9P Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAlAWoUAACgkQC3+MBN1Mb4i1lwCgn/EPFLhvIMd9mjnly2r5h9hL hgAAoPaXJD8KWFJFeXMHZwo3kEFA42cH =8qAA -----END PGP SIGNATURE----- --zUahwhnDqgGY+q9P--