From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Dharm Subject: Re: [example PATCH - not for applying] exclude certain commands Date: Thu, 24 Apr 2003 12:14:09 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20030424121409.C10511@one-eyed-alien.net> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-md5; protocol="application/pgp-signature"; boundary="kVXhAStRUZ/+rrGn" Return-path: Received: from ziggy.one-eyed-alien.net ([64.169.228.100]:7945 "EHLO ziggy.one-eyed-alien.net") by vger.kernel.org with ESMTP id S263807AbTDXTCI (ORCPT ); Thu, 24 Apr 2003 15:02:08 -0400 Content-Disposition: inline In-Reply-To: ; from Andries.Brouwer@cwi.nl on Thu, Apr 24, 2003 at 08:59:45PM +0200 List-Id: linux-scsi@vger.kernel.org To: Andries.Brouwer@cwi.nl Cc: James.Bottomley@steeleye.com, afafc@rnl.ist.utl.pt, alan@lxorguk.ukuu.org.uk, greg@kroah.com, linux-scsi@vger.kernel.org, linux-usb-devel@lists.sourceforge.net, mike@hingston.demon.co.uk, stelian@popies.net, torvalds@transmeta.com --kVXhAStRUZ/+rrGn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 24, 2003 at 08:59:45PM +0200, Andries.Brouwer@cwi.nl wrote: > From: Matthew Dharm > Yeah, I know that's a lousy answer. But try to realize that I've been > dealing with a long, slow, and painful discovery process of what the > 'popular OS' uses. >=20 > Yes, I do not blame you at all. Nevertheless, we must only do > things when we really understand why. If a filter is really > necessary we'll find people with problems that are cured only > that way. Today we do not know any such people, it seems. Well, at this point, I guess I should just be happy that something is being done. But, what I'm really afraid of, this coming right back to this point. In the past, I modified the write-protect probing in 2.4.x to be more compa= tible with what usb-storage wanted. But then someone changed it, and it broke. So we changed it again... and it was fine for a while. Then someone changed it in 2.5.x, and it broke again. I guess what's got me frustrated is that this is very fragile, tends to cause serious problems when it fails, often gets changed, and isn't really necessary -- after all, that's why the 'assume write-enabled' code path is there for when the request fails. I've just been around and around this merry-go-round, and I'm trying to get off. We can fix it now, but I am truly afraid that it's going to get broken again in 6 months. And, as for the need for filtering, I know we have such a need. I have several devices on my desk which choke at INQUIRY EVPD -- so right now I filter it in the usb-storage driver. I also have devices that report bogus INQUIRY data lengths, but (luckily) the sanity checks in the INQUIRY probing code generally catch those cases and save us. I've seen devices that choke on START_STOP, unless that START_STOP is an eject command. I fixed this by eliminating the only non-eject use of START_STOP in sd.c -- but how long is it before someone decides they need to use START_STOP for something? We may have fixed MODE_SENSE, but what about the other cases? Matt --=20 Matthew Dharm Home: mdharm-usb@one-eyed-alien.= net=20 Maintainer, Linux USB Mass Storage Driver G: Let me guess, you started on the 'net with AOL, right? C: WOW! d00d! U r leet! -- Greg and Customer=20 User Friendly, 2/12/1999 --kVXhAStRUZ/+rrGn Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE+qDeBIjReC7bSPZARAku1AKCtgXxePcJIJWf+n50fY9Ikq+wQeACfbj0i LAVoYs4M2IqdrrIWaRUQres= =k1Sp -----END PGP SIGNATURE----- --kVXhAStRUZ/+rrGn--