From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH 15a/18] rhashtables: add lockdep tracking to bucket bit-spin-locks. Date: Tue, 05 Jun 2018 07:37:40 +1000 Message-ID: <87bmcqp717.fsf@notabene.neil.brown.name> References: <152782754287.30340.4395718227884933670.stgit@noble> <152782824984.30340.1634082820568216846.stgit@noble> <20180602050322.liesw324q5kawcue@gondor.apana.org.au> <9bea77df-e7db-677a-31b2-710dc6d956ee@gmail.com> <871sdnqty4.fsf@notabene.neil.brown.name> <87po17p8jd.fsf@notabene.neil.brown.name> <20180604181609.sssd4ao6wfwj3il6@netronome.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Cc: Eric Dumazet , Herbert Xu , Thomas Graf , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" To: Simon Horman Return-path: In-Reply-To: <20180604181609.sssd4ao6wfwj3il6@netronome.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, Jun 04 2018, Simon Horman wrote: > On Mon, Jun 04, 2018 at 12:52:54PM +1000, NeilBrown wrote: >>=20 >> Native bit_spin_locks are not tracked by lockdep. >>=20 >> The bit_spin_locks used for rhashtable buckets are local >> to the rhashtable implementation, so there is little opportunity >> for the sort of misuse that lockdep might detect. >> However locks are held while a hash function or compare >> function is called, and if one of these took a lock, >> a misbehaviour is possible. >>=20 >> As it is quite easy to add lockdep support this unlikely >> possibility see to be enough justification. > > nit: s/see/seems/ > Thanks :-) I've made that change for when I formally submit. Thanks, NeilBrown >>=20 >> So create a lockdep class for bucket bit_spin_lock as attach >> through a lockdep_map in each bucket_table. >>=20 >> With the 'nested' annotation in rhashtable_rehash_one(), lockdep >> correctly reports a possible problem as this lock it taken >> while another bucket lock (in another table) is held. This >> confirms that the added support works. >> With the correct nested annotation in place, lockdep reports >> no problems. >>=20 >> Signed-off-by: NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlsVsSQACgkQOeye3VZi gbmEww//cMQG+c3/pbeLG/h4fUrcJmCLEmAk3V41/BxPNKCmfjvvL3No063PNJ/6 9zW4PUJKRCOIh6eiuDaMzAo02oCeO6KLuBWUPcwJa3bkl1J3K8FHGcsh2yC6wKPy 8O1Z00ivQ/iP6X9vi4raG/s+wiqCrRas2Olcp9MU+XURPORiV2AqdTdeIco6mfuH vr5HePpBIwdd3w4Z3Eb0Zgf2sanPIixJPwB1hmiUhV+rE1jiI5P3185QSFe63jny RzDudmuMDs41PxUX6LKx+MS4lCfAHkJDtiW0W322rxgd6qdE8oha3iyveWKmXsLd RqX9E1/XWxZBDICIKX467NCjyjjClY4eMNWrIeM6uQnHmI16lnoUUw7PqrUE3mqJ rTWqAa6mhZnh79w2flPpi/GG5f1Rx59u86yf28X+PQXTmT7p/gVNdU3HlbSNV+v+ V4+24l5Ds5pLwk++2odzQFGDLTPSRcme1APoTfBoReiuA2uWHVlkfIjZw9LPFkhC d2Y71PJsUkwkXX3ug0otG+dnttZoOWoWlfZmhYmJp0sqKvciOOJH/Ngq00iJ/xca dpg55NYtGxz2ue2biaFh3Yc7dmTGbVX6+Yx+Rt8aVbtxhy5PAPz9f/V9i4inBJS5 G6mt8w+APDLh9FibOtfNgb1XtASSmAvHCoL8w4r1Zul3hHBnnm0= =c8jk -----END PGP SIGNATURE----- --=-=-=--