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Wed, 28 Oct 2026 13:43:58 +0000 (GMT) Received: from osiris (unknown [9.68.31.201]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 28 Oct 2026 13:43:58 +0000 (GMT) Date: Wed, 28 Oct 2026 14:43:56 +0100 From: Heiko Carstens To: Ilya Leoshkevich Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v2 04/10] s390/runtime-const: Serialize text patching with text_mutex Message-ID: <20261028134356.8417D0b-hca@linux.ibm.com> References: <20261027143030.3154657-1-hca@linux.ibm.com> <20261027143030.3154657-5-hca@linux.ibm.com> <034dc4fa-520b-4ad5-9d9d-8ae469692698@linux.ibm.com> <20261028110926.8417C5c-hca@linux.ibm.com> <48b38efa-86df-4654-91a9-88c3118ae372@linux.ibm.com> X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48b38efa-86df-4654-91a9-88c3118ae372@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=BOMmP1QG c=1 sm=1 tr=0 ts=6ae1fc23 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=sdVNXsAZ8R04oH_nJ-YA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: sroLhmCdr0Edsmksvub_bg88hNIr5LVt X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDI4MDA1NCBTYWx0ZWRfX9yQv8GBDQVyu CTJnIS8lC/qbuL1xeFx5f93wkP9P34x+MCSLmjyxWiDL90MXCpbVzbZx5DCr+fMhLFD1tSd5Yi3 BduhGlwJv5q+LbZOwSinDysRvytSyGejQn9EZf3b/oN7pVREJsUnfOyOD6kABEW72wllKwXqQu9 3ANgxMjEtfOyM8y1QIFBG+LYPg1Jy/b0jvztXZwCP2sbw4w8FPpcg597p0v9S3cpzpMCAbJFP5l E/+LI5gWEZ4/5HfKy1d+e3++AQwc2mgcFCprL1gvFdLXFoaxs7GdtW9F/1LuR+p4NjppIoaJWeo SFmsO+girwmgif0NxhO2gcjBX2vVzsS7K0Z+CiKKVdJUXKlzxtwJu3lwXIAz85Qo8IU2W+Unm8W PCallGtEB9MKa7GptSPNQowP2kvbq23kc2VBrXb9iT714a31a7iNYyAR65f1dceIYX3P5Yk7Tdi wjxTmjumiKWPHdm1N6A== X-Proofpoint-GUID: sroLhmCdr0Edsmksvub_bg88hNIr5LVt X-Proofpoint-Spam-Info: AW1haW4tMjYxMDI4MDA1NCBTYWx0ZWRfX4doLCR4J/cE6 HFHRb2s5zYBN/rP/zf17zZPD8OYT6zTWbyugHzovZG340hs8K9PYV7B6Jl+A+SHVIeVu4UkUkLJ TNSNPcnQr00GnSd1Fzjc8+WXF7s6p5c= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-28_04,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 malwarescore=0 clxscore=1015 spamscore=0 phishscore=0 adultscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610280054 On Wed, Oct 28, 2026 at 01:22:30PM +0100, Ilya Leoshkevich wrote: > On 10/28/26 12:09, Heiko Carstens wrote: > > On Wed, Oct 28, 2026 at 11:58:27AM +0100, Ilya Leoshkevich wrote: > > > > @@ -88,6 +89,7 @@ static inline void __runtime_fixup_mask(void *where, unsigned long val) > > > > static inline void runtime_const_fixup(void (*fn)(void *, unsigned long), > > > > unsigned long val, s32 *start, s32 *end) > > > > { > > > > + guard(mutex)(&text_mutex); > > > > while (start < end) { > > > > fn(*start + (void *)start, val); > > > > start++; > > > > > > Interesting, so clang is able to propagate context even through indirect > > > calls without explicit annotations? > > > > There is no clang context analysis involved here - this is purely lockdep > > based (with the last patch of this series, which adds lockdep_assert_held() > > to s390_kernel_write()). > > Ah, I see, it's stated right in the first line of the cover letter. > Did you consider using it though? Yes I did, but if I add __must_hold(text_mutex) to the inlined s390_kernel_write(), then clang cannot prove at all call sites that the lock is actually held - so plenty of additional annotations would be required (if possible at all), and then I decided to drop that approach and rely only on lockdep.