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Fri, 18 Sep 2026 11:02:04 +0000 (GMT) Received: from osiris (unknown [9.111.38.246]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 18 Sep 2026 11:02:04 +0000 (GMT) Date: Fri, 18 Sep 2026 13:02:03 +0200 From: Heiko Carstens To: Mark Rutland Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Mete Durlu , Peter Zijlstra , Juergen Christ , Ilya Leoshkevich , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v2 12/12] s390/percpu: Rework to simplify percpu_entry() and percpu_exit() Message-ID: <20260918110203.20386F2b-hca@linux.ibm.com> References: <20260918084842.2333237-1-hca@linux.ibm.com> <20260918084842.2333237-13-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE4MDE1NCBTYWx0ZWRfX8vN9k6tLa5tC qKN96gJU8XJCk6sOO3PyK5BOVkqOzaoLnPCDRRTNx3lFwRqOBwuTa2A/XvimcIj/pjP+cBKiazZ sxv7PHqvAUy/0oWy28nfCdz3iaK/Zu9xnye/q4yQHffhmlARcpwcrqo3yXmrZXDjCVe+d5yNkVh JCfeXoaaN1QKVqlVEcHqZUtf6TGpWH60gAi94BrZW+us8ZLU/s5+J0Fvv90GVD3SM2OWaikld8K 91WmC8M2yPxhP/4BsJWoB/BAuctw07qOe2DI0mPNPbpIto1tC3RKKMwTZGPJyDpZAyHrhMGrveI 2yo9jS5eJMwHravIyaxYJS/XXk8a7cwdDWubmfQYukyXr2kLN4AxFRKcZXfxS2gtEuFdfMfCJif w3XGsypLH5Gl1/aojhEordfa/P61yTKmh4ZIlwVMEF81ZiZ3fSYZ0htuRKQ2sOSxR2TE4Wap+ZP dACnnGImHgZHQOWnvuw== X-Proofpoint-ORIG-GUID: YPTu6fwYnFyVPJY1As4Q9gTDvpW9foUx X-Proofpoint-GUID: YPTu6fwYnFyVPJY1As4Q9gTDvpW9foUx X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE4MDE1NCBTYWx0ZWRfXwrT3tUHhEWw+ TWrzPVaOTZB79Rn3G+wxXP1yAJOL1qs4yMcAlks5+zSs4xjfSrj5xlgeEWdwpX34KvGqitK6ymv HWh3ptCBrJbxBRpHGfJqnMBZRwnfreI= X-Authority-Analysis: v=2.4 cv=cY9HPXDM c=1 sm=1 tr=0 ts=6aad1a31 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=xIGoFdqxBrF3HhsM5RMA:9 a=CjuIK1q_8ugA:10 a=zZCYzV9kfG8A:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-18_03,2026-09-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 bulkscore=0 clxscore=1015 suspectscore=0 impostorscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609180154 On Fri, Sep 18, 2026 at 11:40:21AM +0100, Mark Rutland wrote: > On Fri, Sep 18, 2026 at 10:48:42AM +0200, Heiko Carstens wrote: > > +#define __PCPU_AGRK(regptr, regpcp, regoff) \ > > + " agrk " regptr "," regpcp "," regoff "\n" > > + > > +#define __PCPU_BEGIN(lcreg, lcoff, regpcp, regoff, regptr) \ > > + __PCPU_MVIY_REGS(lcreg, regpcp, regoff) \ > > + __PCPU_LG(regoff, lcoff) \ > > + __PCPU_AGRK(regptr, regpcp, regoff) > > Since percpu_exit() relies on regptr being regoff + 1, maybe it's worth > having a check here to verify that? Perhaps in __PCPU_MVIY_REGS() with > the uniqueness check. > > Hopefully that never goes wrong, but catching a violation at build time > might save some future pain. Yes, that makes sense. Especially considering that there was already a previous bug which could have been caught at build time. Thanks a lot for taking a look!