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smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-c2dff70000001609-c3-6a5088f7d053 Date: Fri, 10 Jul 2026 14:53:54 +0900 From: Byungchul Park To: Gary Guo Cc: linux-kernel@vger.kernel.org, max.byungchul.park@gmail.com, kernel_team@skhynix.com, torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com, harry.yoo@oracle.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, boqun.feng@gmail.com, longman@redhat.com, yunseong.kim@ericsson.com, ysk@kzalloc.com, yeoreum.yun@arm.com, netdev@vger.kernel.org, matthew.brost@intel.com, her0gyugyu@gmail.com, corbet@lwn.net, catalin.marinas@arm.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, luto@kernel.org, sumit.semwal@linaro.org, gustavo@padovan.org, christian.koenig@amd.com, andi.shyti@kernel.org, arnd@arndb.de, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mcgrof@kernel.org, petr.pavlu@suse.com, da.gomez@kernel.org, samitolvanen@google.com, paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, chuck.lever@oracle.com, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, trondmy@kernel.org, anna@kernel.org, kees@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, mark.rutland@arm.com, ada.coupriediaz@arm.com, kristina.martsenko@arm.com, wangkefeng.wang@huawei.com, broonie@kernel.org, kevin.brodsky@arm.com, dwmw@amazon.co.uk, shakeel.butt@linux.dev, ast@kernel.org, ziy@nvidia.com, yuzhao@google.com, baolin.wang@linux.alibaba.com, usamaarif642@gmail.com, joel.granados@kernel.org, richard.weiyang@gmail.com, geert+renesas@glider.be, tim.c.chen@linux.intel.com, linux@treblig.org, alexander.shishkin@linux.intel.com, lillian@star-ark.net, chenhuacai@kernel.org, francesco@valla.it, guoweikang.kernel@gmail.com, link@vivo.com, jpoimboe@kernel.org, masahiroy@kernel.org, brauner@kernel.org, thomas.weissschuh@linutronix.de, oleg@redhat.com, mjguzik@gmail.com, andrii@kernel.org, wangfushuai@baidu.com, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-i2c@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, rcu@vger.kernel.org, linux-nfs@vger.kernel.org, linux-rt-devel@lists.linux.dev, 2407018371@qq.com, dakr@kernel.org, miguel.ojeda.sandonis@gmail.com, neilb@ownmail.net, bagasdotme@gmail.com, wsa+renesas@sang-engineering.com, dave.hansen@intel.com, geert@linux-m68k.org, ojeda@kernel.org, alex.gaynor@gmail.com, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v19 31/40] dept: assign unique dept_key to each distinct wait_for_completion() caller Message-ID: <20260710055354.GA37630@system.software.com> References: <20260706061928.66713-1-byungchul@sk.com> <20260706061928.66713-32-byungchul@sk.com> Precedence: bulk X-Mailing-List: linux-block@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: User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0xTZxzG857zngsdHYdO4ztrNlNHWJhTt7jln+gu2RdPspmxkS1u+zCb 9QTKVVvlssSsKKhBcAzXMtqJXFxtAFktDgfSBYt0NmjWakJqp7OSBlML6DqEIdjuUGPmt1+e 53mf5//h5WlVK7ua15fukQyl2mINq8CK6fT2V/89nFu46YcZNdy4FWFgvHoYw4PZwxge2c5x 4O/tRjC/aKOhdiApa01eDmYX/uTAXI0g6fYisASaaPjHmWAhNhJHYL4dYaE5Wo3hnr0eQXR0 GyRv3qHAHklQELPcl02zH0E8Gkbgduxn4VrkWfCZj7AwHfiRghknC2373QxMhtwUWI67MAyE BzkIxJYo6HZth1v2SQxjjR2UPMKC5cwqsDUfoMB8+jwFC/YuDi533sBgN2WB7co1BiYcVg6S bWXg+2ucgXOmMAeu66PydOgVaD94EsOQ24eh3vkLAybbPAP+4TEGrnb7Mfx8J0jBmPcShr4r l2mYO6oG/3cNDJye6WDh2MwkgticnX5XJ87XHsViV18/Jfa09iBx8WETEmsbZRqZukeLNX0V 4k9jU6w4YL3JiTW/hTixzbVXrLk4zYh9jhyxcyhKie3xB4wYir2V+/Lniq06qVhfLhk2vr1T UTB6sh/vas2sHJwcok3ob2UdSuOJsJlEL52in/DExSFmmbGQRaYPTHHLzArZJBhcSGVWCC8S V1cHVYcUPC20vECuzvlSD54TisiSI5oKKQUgI+OdqZBKaEDE+9DGPDYyia8lgpeZFnJIMBGV Q7zManIqwS/LacIb5P7ZeGp4pbCODPf/nuohwkQa+f5sEj++9HlywRHEjUiwPlVrfarW+n9t G6K7kEpfWl6i1Rdv3lBQVaqv3PBVWYkLyb/Wvm/pi19R3J/nQQKPNOnKTd98WKhitOXGqhIP IjytWaEMr5ElpU5b9bVkKPvSsLdYMnqQmseaVcrX5yp0KiFfu0cqkqRdkuGJS/Fpq01IO5G+ bfexuy25RxZbErfzQmcKF/Kuf2LJL6rgwp7eWemjei9nXGvO3nmionLjt1M7mo/bMg6Onrfm 1wWysne8r165fp9ljY6d3f2S2lkXWMoteedCQc9na/9Yt5j5waNPuYZDvYcKleTN97ZnfNzB ntBsHcx4Jr6eOD3m5tot9pq7WzTYWKB9LYc2GLX/Ae5QvRexAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0xTZxjH877n9PTQWT0UCCdek5rFhEyRTZIn2bKLmXpivPCNhCzRRk9G 5aJpEWUJU6iN1ampTVqk9QJFKitMsCCOSyMBrUPnbLlIo7DCUuu6giBQCJeWnWKMfnnye57n /8vzfnhpQrYkWk0r8wt4Vb4iV05JSMm+LzWbZ3UZR7bet6aCTnsKBn1+ETwv6SAhPK0j4Wp9 HQURyz0x6BzlIvhjoJQE9+1aBL6wDsHsgoUAbcsSCRGDSwzTcy/FYCxBsOR0ITB5DAR43fcJ qGsqwTDVEKUg1DWJwDjip6AsWELCuO0CAnPAIobgw10w5msTwdLQawwDM6MIbP4oBn/HWQQR Uw7csDYKummCgoWnzwgoM7oRVI4METAZHEbQ5PobgbOmlIJX+rsE9PpXQl94nIJu4y8UjHmu YnjTQEFFqVMEnj9DCK5ZDAgCL5wYNFX1FJiuOUhoGW4Vgye0iGHQZMBQ69gLPluAhCd6Kxae K6TuJIOlTIOF8i8G429tGOZsdvG31Yib1V4iOXtjM+a0PRGKq7teh7iFeQPipqs1BKfVC23X 6DjBnWk8wVU/GaW4+XA/xTlnKkjusZXlbp6bx9zlp5u5FvOQOOO7LMlXh/lcZSGvSv36oCT7 4c1m8tj1+JOtgXbiNHorPY/iaJbZxv7zoF0UY5L5lB3TjIpjTDGbWK93johxIrOBddit+DyS 0ARTvp7tmeleFhKYHHaxJrgckjLAdj2vWg7JmIuIdc1bRO8W8Wx3uZ+MMcGksN5oUAjRAq9h b0Xp2DiOSWcnmiaXDycxG9mO5kdYj6Tmj2zzR7b5g12BCDtKVOYX5imUuelb1DnZRfnKk1sO Hc1zIOFb2ooXL/+Opnt3dSKGRvIV0q2n9h+RiRSF6qK8TsTShDxROrxWGEkPK4p+4lVHD6iO 5/LqTrSGJuXJ0t2Z/EEZ86OigM/h+WO86v0W03GrT6NNrXcKip9lq88W7zBMeONTd//X03ku lLh36pXsojnl5aNP0jrazUWRAcnaK+4+Q8iV3PD5TllCZtKqxuTt4YxfM+9VfpEU/N7zwD5Y 2+/ybf+mH+uyVuzYqV73Q3Pv20D6SNvdqopV6/V861Rl9K8+RVZC8DO38/XjffXMngvlB9J+ lpPqbEVaCqFSK/4HtzJC/ZIDAAA= X-CFilter-Loop: Reflected On Tue, Jul 07, 2026 at 03:18:29PM +0100, Gary Guo wrote: > On Mon Jul 6, 2026 at 7:19 AM BST, Byungchul Park wrote: > > wait_for_completion() can be used at various points in the code and it's > > very hard to distinguish wait_for_completion()s between different usages. > > Using a single dept_key for all the wait_for_completion()s could trigger > > false positive reports. > > > > Assign unique dept_key to each distinct wait_for_completion() caller to > > avoid false positive reports. > > > > While at it, add a rust helper for wait_for_completion() to avoid build > > errors. > > This will cause Rust code to share the same dept_key, so it will have all the > false positives that the change is trying to avoid. Thank you for the input. > In general it is easy to create Rust bindings for static inline C functions > because it'll be just some computation, while creating bindings for C > function-like macros that define additional statics can be challenging. > > Is dept_key similar to lock_class_key, where only the address matters? If so, > the approach that I use in > https://lore.kernel.org/rust-for-linux/DJP0CDOR98N5.29BK8PUFRWRUK@garyguo.net Yes, dept_key is similar to lock_class_key. IIUC, the way you tried for lock_class_key can be applied to DEPT too. I will do: 1) add 'key' parameter to sdt_might_sleep_start_timeout() 2) introduce init_completion_dkey() to allow custom keys 3) remove init_completion_dmap() and adjust the existing users Just in case, it's worth noting that the custom keys must be well-managed using e.g. dept_key_destroy() when the key gets freed. Byungchul > could be used for dept_key as well, then we can keep Rust `wait_for_completion` > still a function; otherwise we have to turn it into a macro too on the Rust side > to create such statics, which isn't ideal. > > Best, > Gary > > > > > Signed-off-by: Byungchul Park > > --- > > include/linux/completion.h | 100 +++++++++++++++++++++++++++++++------ > > kernel/sched/completion.c | 60 +++++++++++----------- > > rust/helpers/completion.c | 5 ++ > > 3 files changed, 120 insertions(+), 45 deletions(-)