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Wed, 8 Apr 2020 22:55:39 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A3268112061; Wed, 8 Apr 2020 22:55:29 +0000 (GMT) Received: from LeoBras (unknown [9.85.164.111]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 8 Apr 2020 22:55:29 +0000 (GMT) Message-ID: <49614a1c3fba382d2a7bca0574015438dd50b843.camel@linux.ibm.com> Subject: Re: [PATCH v3 1/1] ppc/crash: Reset spinlocks during crash From: Leonardo Bras To: Michael Ellerman , Nicholas Piggin , Alexios Zavras , Benjamin Herrenschmidt , Christophe Leroy , Greg Kroah-Hartman , Enrico Weigelt , Paul Mackerras , peterz@infradead.org, Thomas Gleixner Date: Wed, 08 Apr 2020 19:55:19 -0300 In-Reply-To: <87v9majhh2.fsf@mpe.ellerman.id.au> References: <20200401000020.590447-1-leonardo@linux.ibm.com> <871rp6t9di.fsf@mpe.ellerman.id.au> <02e74be19534ab1db2f16a0c89ecb164e380c12a.camel@linux.ibm.com> <1585895551.7o9oa0ey62.astroid@bobo.none> <87v9majhh2.fsf@mpe.ellerman.id.au> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-rW4zuZR8MtcT2HNBtaaN" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-08_09:2020-04-07, 2020-04-08 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 mlxlogscore=957 clxscore=1015 mlxscore=0 impostorscore=0 adultscore=0 phishscore=0 suspectscore=0 malwarescore=0 priorityscore=1501 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004080152 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" --=-rW4zuZR8MtcT2HNBtaaN Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2020-04-08 at 22:21 +1000, Michael Ellerman wrote: [...] > > According with LoPAR, for both of these rtas-calls, we have: > >=20 > > For the PowerPC External Interrupt option: The call must be reentrant > > to the number of processors on the platform. > > For the PowerPC External Interrupt option: The argument call buffer for > > each simultaneous call must be physically unique. >=20 > Oh well spotted. Where is that in the doc? >=20 > > Which I think means this rtas-calls can be done simultaneously. >=20 > I think so too. I'll read PAPR in the morning and make sure. >=20 > > Would it mean that busting the rtas.lock for these calls would be safe? >=20 > What would be better is to make those specific calls not take the global > RTAS lock to begin with. >=20 > We should be able to just allocate the rtas_args on the stack, it's only > ~80 odd bytes. And then we can use rtas_call_unlocked() which doesn't > take the global lock. Hello Michael, I did the simplest possible version of this change: http://patchwork.ozlabs.org/patch/1268371/ Where I create a rtas_call_reentrant(), and replace rtas_call() for that in all the possible calls of "ibm,int-on", "ibm,int-off",ibm,get- xive" and "ibm,set-xive". At first, I was planning on creating a function that tells if the requested token is one of above, before automatically choosing between the common and reentrant versions. But it seemed like unnecessary overhead, since the current calls are very few and very straight.=20 What do you think on this? Best regards, Leonardo Bras --=-rW4zuZR8MtcT2HNBtaaN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEMdeUgIzgjf6YmUyOlQYWtz9SttQFAl6OVlcACgkQlQYWtz9S ttTSNxAA2WHqbEvJ/q09rkldKj1jNwGATvtXn1UHGLMxi6baM0un8mwQGGA9rRk2 mYCS9d5t6SUFax/0dOd3k4jMZJL9EYLvArqakuNgt+HINbholuBjDR6hRMHSOOxq YfIw0UQgsRlpIqM4qAUEr6c117sArf+PMMIKUSsN80JlVuQPMqZbGboBS9P70bjA 26tjVVBWBE1D05+QXrW3nh/bMgCoJ/wPujv8cFhrFEtlnxvQiA2kesnlSKn/Ijx/ Ne5xRD+erktHo88YXQ306BFBR4aCKE1pdcgtA5R+IaR5LPxAb0duqHbbKjBstAtc J2hTn74nURuRvQAZ+T5G2dVFtu/9yJwwh1p0zQU1G04m6emyn5w4e5JKc00Kk6jC vsYlt51nH2RJiKomGCw9GVwtEx9gU52dYaAKVzT5rvqUlRjPu/diDdF24mQ74zUd +8oOMfbdnbU84CkXfD4LMe0RPJURgDuHdSOteos1ycYwL6kAKZb1CGiE/uJqWyPn tnUReM4W+RWgQb4BjMRjhoYZciw5j/Vhim9s22G3tZGhOA4tYu2x/5UYWKgjg1zl UtAbKTbM2U/bmD/+RzEQA5ZbWvR+qkeLsCd2MNFfFs8ZRkUQlIzumXWOoPhLxh1C nJ3ePZ65jEvdW0EXxpSwV4NwyRbxMOEEiHYvLuEgerU2wLbbR7E= =y/4S -----END PGP SIGNATURE----- --=-rW4zuZR8MtcT2HNBtaaN--