From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751476AbdASJQE (ORCPT ); Thu, 19 Jan 2017 04:16:04 -0500 Received: from mail-pf0-f195.google.com ([209.85.192.195]:33818 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbdASJQB (ORCPT ); Thu, 19 Jan 2017 04:16:01 -0500 Date: Thu, 19 Jan 2017 17:16:27 +0800 From: Boqun Feng To: Byungchul Park Cc: peterz@infradead.org, mingo@kernel.org, tglx@linutronix.de, walken@google.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, npiggin@gmail.com Subject: Re: [PATCH v5 01/13] lockdep: Refactor lookup_chain_cache() Message-ID: <20170119091627.GG15084@tardis.cn.ibm.com> References: <1484745459-2055-1-git-send-email-byungchul.park@lge.com> <1484745459-2055-2-git-send-email-byungchul.park@lge.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="VkVuOCYP9O7H3CXI" Content-Disposition: inline In-Reply-To: <1484745459-2055-2-git-send-email-byungchul.park@lge.com> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --VkVuOCYP9O7H3CXI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 18, 2017 at 10:17:27PM +0900, Byungchul Park wrote: > Currently, lookup_chain_cache() provides both 'lookup' and 'add' > functionalities in a function. However, each is useful. So this > patch makes lookup_chain_cache() only do 'lookup' functionality and > makes add_chain_cahce() only do 'add' functionality. And it's more > readable than before. >=20 > Signed-off-by: Byungchul Park > --- > kernel/locking/lockdep.c | 129 +++++++++++++++++++++++++++++------------= ------ > 1 file changed, 81 insertions(+), 48 deletions(-) >=20 > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index 4d7ffc0..f37156f 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -2109,15 +2109,9 @@ static int check_no_collision(struct task_struct *= curr, > return 1; > } > =20 > -/* > - * Look up a dependency chain. If the key is not present yet then > - * add it and return 1 - in this case the new dependency chain is > - * validated. If the key is already hashed, return 0. > - * (On return with 1 graph_lock is held.) > - */ I think you'd better put some comments here for the behavior of add_chain_cache(), something like: /* * Add a dependency chain into chain hashtable. *=20 * Must be called with graph_lock held. * Return 0 if fail to add the chain, and graph_lock is released. * Return 1 with graph_lock held if succeed. */ Regards, Boqun > -static inline int lookup_chain_cache(struct task_struct *curr, > - struct held_lock *hlock, > - u64 chain_key) > +static inline int add_chain_cache(struct task_struct *curr, > + struct held_lock *hlock, > + u64 chain_key) > { > struct lock_class *class =3D hlock_class(hlock); > struct hlist_head *hash_head =3D chainhashentry(chain_key); > @@ -2125,49 +2119,18 @@ static inline int lookup_chain_cache(struct task_= struct *curr, > int i, j; > =20 > /* > + * Allocate a new chain entry from the static array, and add > + * it to the hash: > + */ > + > + /* > * We might need to take the graph lock, ensure we've got IRQs > * disabled to make this an IRQ-safe lock.. for recursion reasons > * lockdep won't complain about its own locking errors. > */ > if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) > return 0; [...] --VkVuOCYP9O7H3CXI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEj5IosQTPz8XU1wRHSXnow7UH+rgFAliAg+cACgkQSXnow7UH +rh2Jgf/fmUbrOVM0V2wjEeynnt2EYwHfMJfx5jihIcOU13CammK9+rMyHHkQgoL Kx/0AXWOme22RbvRmRsCsCkp6zMFXFwOb0Ax99Tlz+oi3ggRXQB3aHxxxNNkYZef iIJuGqgR/R5PnypA9cAcUPluXErXt5P9Ie9DSXXSMgn4c7r8NMnn2BVKxG1AjUHK /kLyYvlkV+3mKHnxkP24WikrFuRSwtuZ6g/ymV1ic6MDczouSEZBRPfKku2SduBJ hpQz+ZwiCRjHDqy6R45ZnLN8k9tUye0NGv2XvMe53b3sYj8SODl5j1NuXduRW30Q TKhK2At4KXtQMtNtCGdzR1bPe8q3nQ== =qFe1 -----END PGP SIGNATURE----- --VkVuOCYP9O7H3CXI--