From owner-freebsd-current Tue Jul 10 23:39:11 2001 Delivered-To: freebsd-current@freebsd.org Received: from rina.r.dl.itc.u-tokyo.ac.jp (cvsup2.r.dl.itc.u-tokyo.ac.jp [133.11.199.247]) by hub.freebsd.org (Postfix) with ESMTP id E964637B401; Tue, 10 Jul 2001 23:39:07 -0700 (PDT) (envelope-from tanimura@r.dl.itc.u-tokyo.ac.jp) Received: from rina.r.dl.itc.u-tokyo.ac.jp (localhost [127.0.0.1]) by rina.r.dl.itc.u-tokyo.ac.jp (8.11.3+3.4W/3.7W-rina.r-20010412) with ESMTP id f6B64ht61439 ; Wed, 11 Jul 2001 15:07:26 +0900 (JST) Message-Id: <200107110607.f6B64ht61439@rina.r.dl.itc.u-tokyo.ac.jp> Date: Wed, 11 Jul 2001 15:04:43 +0900 From: Seigo Tanimura To: tanimura@r.dl.itc.u-tokyo.ac.jp Cc: bright@sneakerz.org, jake@FreeBSD.org, jhb@FreeBSD.org, current@FreeBSD.org Subject: Re: Lock of struct filedesc, file, pgrp, session and sigio In-Reply-To: In your message of "Wed, 11 Jul 2001 10:44:21 +0900" <200107110144.f6B1iL080250@silver.carrots.uucp.r.dl.itc.u-tokyo.ac.jp> References: <20010531124007.B57907@dragon.nuxi.com> <20010531130155.A58258@dragon.nuxi.com> <200106011228.f51CSvD46848@rina.r.dl.itc.u-tokyo.ac.jp> <20010602125223.J31257@dragon.nuxi.com> <200106040748.f547mUD53783@rina.r.dl.itc.u-tokyo.ac.jp> <200106181004.f5IA4VD63112@rina.r.dl.itc.u-tokyo.ac.jp> <200107020812.f628CfK44241@rina.r.dl.itc.u-tokyo.ac.jp> <20010707164249.C88962@sneakerz.org> <20010709032044.B1894@sneakerz.org> <200107110144.f6B1iL080250@silver.carrots.uucp.r.dl.itc.u-tokyo.ac.jp> User-Agent: Wanderlust/1.1.1 (Purple Rain) SEMI/1.13.7 (Awazu) FLIM/1.13.2 (Kasanui) MULE XEmacs/21.1 (patch 14) (Cuyahoga Valley) (i386--freebsd) Organization: Digital Library Research Division, Information Techinology Centre, The University of Tokyo MIME-Version: 1.0 (generated by SEMI 1.13.7 - "Awazu") Content-Type: text/plain; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Wed, 11 Jul 2001 10:44:21 +0900, Seigo Tanimura said: Alfred> I'm also quite sure that you can't call the ktrace functions with Alfred> any mutexes held so the code is doing to need some help, basically Alfred> the trick in trapsig() and postsig() is to generate the ktrace Alfred> IO after the locks have been dropped, this means somehow caching Alfred> the info sent to ktrace where it's currently called, and calling Alfred> it later with the cached info after the locks are dropped. Seigo> We can cache ktrace information into struct proc and mark the Seigo> existence of cache in p_traceflag. Then we send the information to Seigo> ktrace upon returning from trapsignal() or CURSIG(), or in sigexit(). The problem has turned out to be even worse. msleep() and cv_*wait*() might receive a mutex held by curproc. As we cannot release the mutex to sleep in ktrwrite() during msleep() or cv_*wait*(), it is also necessary to cache information sent to ktrcsw(). Is it not feasible to examine the existence of cached ktrcsw() information upon every single call of msleep() and cv_*wait*() in order to flush the cached information. Instead of that, we should watch for release of mutexes. When a process no longer holds any mutexes except for Giant, it is safe to flush cached information to ktrace. -- Seigo Tanimura To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message