Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756086AbYHUKUa (ORCPT ); Thu, 21 Aug 2008 06:20:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753009AbYHUKUV (ORCPT ); Thu, 21 Aug 2008 06:20:21 -0400 Received: from ozlabs.org ([203.10.76.45]:39631 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752899AbYHUKUT (ORCPT ); Thu, 21 Aug 2008 06:20:19 -0400 Subject: Re: [Cbe-oss-dev] powerpc/cell/oprofile: fix mutex locking for spu-oprofile From: Michael Ellerman Reply-To: michael@ellerman.id.au To: Arnd Bergmann Cc: cbe-oss-dev@ozlabs.org, Robert Richter , linux-kernel , linuxppc-dev@ozlabs.org, oprofile-list@lists.sourceforge.net, cel In-Reply-To: <200808211014.42683.arnd@arndb.de> References: <1217620879.15667.145.camel@carll-linux-desktop> <200808201519.19453.arnd@arndb.de> <18604.60738.523963.886786@drongo.ozlabs.ibm.com> <200808211014.42683.arnd@arndb.de> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-JqgvIhwwsQmTK+CI1mt6" Date: Thu, 21 Aug 2008 20:20:10 +1000 Message-Id: <1219314010.7827.4.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1979 Lines: 60 --=-JqgvIhwwsQmTK+CI1mt6 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2008-08-21 at 10:14 +0200, Arnd Bergmann wrote: > On Thursday 21 August 2008, Paul Mackerras wrote: > > Arnd Bergmann writes: > >=20 > > > Paul, any chance we can still get this into 2.6.27? > >=20 > > Possibly. We'll need a really good explanation for Linus as to why > > this is needed (what regression or serious bug this fixes) and why it > > is late. Can you send me something explaining that? >=20 > The patch does not fix a regression, the spu-oprofile code basically neve= r > worked. With the current code in Linux, samples in the profile buffer > can get corrupted because reader and writer to that buffer use different > locks for accessing it. Actually for me it worked[1] a reasonable amount of the time, enough to be useful. So the spu-oprofile code has always been broken in this way, but it's not always fatal. So the patch doesn't fix a regression, but it fixes a serious user-visible bug, which makes it legit rc4 material IMHO. [1] that was late last year, so possibly a kernel or two ago. cheers --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-JqgvIhwwsQmTK+CI1mt6 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBIrUFadSjSd0sB4dIRAlHKAJ4oBE3v9ppU4oEOPWkj14wwKwLLSQCgs6iu GyCYGC3opKCqo8n1WiZtmME= =uCJc -----END PGP SIGNATURE----- --=-JqgvIhwwsQmTK+CI1mt6-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/