Date: Wed, 15 Sep 2010 18:04:12 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Attilio Rao <attilio@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212661 - head/sys/dev/aac Message-ID: <20100915150412.GM2465@deviant.kiev.zoral.com.ua> In-Reply-To: <AANLkTikMxAZDa9KGvY-aPfCJ=gQL0gNpF5Marsbw-Wuv@mail.gmail.com> References: <201009151424.o8FEOLZE039185@svn.freebsd.org> <20100915145209.GK2465@deviant.kiev.zoral.com.ua> <AANLkTikMxAZDa9KGvY-aPfCJ=gQL0gNpF5Marsbw-Wuv@mail.gmail.com>
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--tI9tJD/InAKWF1Ci Content-Type: text/plain; charset=koi8-r Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 15, 2010 at 04:57:15PM +0200, Attilio Rao wrote: > 2010/9/15 Kostik Belousov <kostikbel@gmail.com>: > > On Wed, Sep 15, 2010 at 02:24:21PM +0000, Attilio Rao wrote: > >> Author: attilio > >> Date: Wed Sep 15 14:24:21 2010 > >> New Revision: 212661 > >> URL: http://svn.freebsd.org/changeset/base/212661 > >> > >> Log: > >> =9A Fix bogus busying mechanism from cdevsw callbacks: > >> =9A - D_TRACKCLOSE may be used there as d_close() are expected to matc= h up > >> =9A =9A d_open() calls > > VFS is not very good at properly calling VOP_CLOSE(). As example, prema= ture > > vnode reclaim due to devfs unmount would cause VOP_CLOSE() to be called > > only once despite the number of opens being =9A> 1. >=20 > Yes. > That makes implementing a similar semantic in drivers very difficult > and not very well fixable, in particular within the d_* callbacks. > I'm seriously wondering if we might just make a shortcut just for > supporting such a feature (busying the device on real devfs entry > activity) as several of them may be needing and may be probabilly > needing to be 100%. > Luckilly, it seems that such paths are not experienced very frequently. I am not sure what do you mean by "busying the device on real devfs entry activity". Is the operation made by dev_refthread() and friends enough ? Device cannot be destroyed by destroy_dev() until all threads leave the cdevsw methods. --tI9tJD/InAKWF1Ci Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkyQ4GwACgkQC3+MBN1Mb4hezwCgkXk6Fq5UUL8fgIO6Y8a7Lv9a m4oAoOSJAfcrcTKBl70Xjuzz1TYYVORC =a12E -----END PGP SIGNATURE----- --tI9tJD/InAKWF1Ci--
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