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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Thorsten Winkler , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Sebastian Ott , Ursula Braun , netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Aliaksei Makarau , Mahanta Jambigi , Halil Pasic Subject: Re: [PATCH 1/1] s390/ism: fix concurrency management in ism_cmd() Message-ID: <20250721123548.31401ac2.pasic@linux.ibm.com> In-Reply-To: References: <20250720211110.1962169-1-pasic@linux.ibm.com> <6b09d374-528a-4a6d-a6c6-2be840e8a52b-agordeev@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzIxMDA4OSBTYWx0ZWRfX6FeVIKVayOkS S/WcbnzdSs9yCZNdP9qIugIlJoaSQXou+BDhVAuD/W2kNp3cYthyLyz5CkhTEMW0vHmsuIpbdQZ PQYpPizpY1F0OQP4zW63RfKdQkaBNiGnCVSZrzY68nCq9925R61z6BjUYpIBFm/1HbfUHDaa41M EEq4jPs1pGLTtYiXtwuPMBboXF0hRPJ0tnFrQ/5BT5iU14ZIwuWV3qzTVrJuCVM97N2OkmzmUE8 RbL+4WiL/LiEGy6rOMgC9NNtHEqYbHP/L4u1LZtyFUHx/3CFwptZCsHaq52wp31V8NuIUwFOwuu ZB2fLJFcjK2SRoqiN+cz63KYZm8p4fgyb8QM2wDSiDzckWO1HQ6JAOsvCsGsHVqNypey79/lneS w9CEOQ3guSNy4BJR6tU/TQkiEXAI519mHL92wCRM9zRJmL69W9PrdTf8Ydo6zUve2Y/sqa7C X-Proofpoint-GUID: NEZNiAB_40OMK-ZM02ykhqsmLTEvM3KM X-Proofpoint-ORIG-GUID: l1MHd4f7ZxURLXhPrHMGUxm4ilWZHldc X-Authority-Analysis: v=2.4 cv=X9RSKHTe c=1 sm=1 tr=0 ts=687e1810 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=Wb1JkmetP80A:10 a=VnNF1IyMAAAA:8 a=pGFWBfxQ5TguR4G5NxIA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-21_03,2025-07-21_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 phishscore=0 malwarescore=0 clxscore=1015 mlxscore=0 spamscore=0 suspectscore=0 mlxlogscore=585 bulkscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2507210089 On Mon, 21 Jul 2025 10:17:30 +0200 Alexandra Winter wrote: > >> + spin_lock_irqsave(&ism->cmd_lock, flags); > > > > I only found smcd_handle_irq() scheduling a tasklet, but no commands issued. > > Do we really need disable interrupts? > > You are right in current code, the interrupt and event handlers of ism and smcd > never issue a control command that calls ism_cmd(). > OTOH, future ism clients could do that. > The control commands are not part of the data path, but of connection establish. > So I don't really expect a performance impact. > I have it on my ToDo list, to change this to threaded interrupts in the future. > So no strong opinion on my side. > Simple spin_lock is fine with me. I agree! My train of thought was, lets go with the safe option and look if the maintainers want something different. I didn't feel confident about trying to understand the details including the contract between the clients and the driver. I will change to simple spin_lock() at the end of the day if nobody objects since the sentiment seems to be going into this direction and spin a v2 no later than on Wed. Thanks for having a look! Regards, Halil