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Mon, 28 Nov 2022 18:26:44 GMT Received: from smtpav02.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6E6CE5805F; Mon, 28 Nov 2022 18:26:43 +0000 (GMT) Received: from smtpav02.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 415DE58073; Mon, 28 Nov 2022 18:26:43 +0000 (GMT) Received: from localhost (unknown [9.211.69.164]) by smtpav02.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 28 Nov 2022 18:26:43 +0000 (GMT) From: Nathan Lynch To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 03/13] powerpc/rtas: avoid device tree lookups in rtas_os_term() In-Reply-To: References: <20221118150751.469393-1-nathanl@linux.ibm.com> <20221118150751.469393-4-nathanl@linux.ibm.com> Date: Mon, 28 Nov 2022 12:26:42 -0600 Message-ID: <875yez9bq5.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: p7IAK6C5NUYMe3UmhbZdUsxUh_xX29JS X-Proofpoint-ORIG-GUID: WTosY1k95NlXZ1Agl-5s8CEpyl4Ogxzr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-28_15,2022-11-28_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxscore=0 suspectscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 mlxlogscore=602 phishscore=0 clxscore=1015 bulkscore=0 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211280132 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: tyreld@linux.ibm.com, nnac123@linux.ibm.com, ldufour@linux.ibm.com, ajd@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" "Nicholas Piggin" writes: > On Sat Nov 19, 2022 at 1:07 AM AEST, Nathan Lynch wrote: >> rtas_os_term() is called during panic. Its behavior depends on a >> couple of conditions in the /rtas node of the device tree, the >> traversal of which entails locking and local IRQ state changes. If the >> kernel panics while devtree_lock is held, rtas_os_term() as currently >> written could hang. > > Nice. > >> >> Instead of discovering the relevant characteristics at panic time, >> cache them in file-static variables at boot. Note the lookup for >> "ibm,extended-os-term" is converted to of_property_read_bool() since >> it is a boolean property, not a RTAS function token. > > Small nit, but you could do that at the query site unless you > were going to start using ibm,os-term without the extended > capability. I'm unsure that this is what you're suggesting, but we don't want to use of_property_read_bool() in this context either, because it has the same undesirable qualities as rtas_token(). > Reviewed-by: Nicholas Piggin Thanks!