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AFNElJ/B1Ow5e3ta2b617s6wGCQI3iS6wQ4GlgrJnn+eQEoN8i81ilQje4sRVrS9eP1oHjlKAitC+8uYIFlDcA==@lists.linux.dev X-Gm-Message-State: AOJu0YweGD8atTCJn01HpnYpkfr1gn3L2mcwAEF97JKZSM8aSzM+2hAx X8rBJh4bs/6RB0NYy14i8swINxpvfyiQ4bz1yen+MUiiaWUnwHw/zLyovbuhA1iLcuwCe43QGzi 91mkyR6777I380XyaRA== X-Received: from wrtw10.prod.google.com ([2002:a5d:608a:0:b0:439:d5c9:3b63]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a5d:5f89:0:b0:43f:e22e:e8da with SMTP id ffacd0b85a97d-4493d7fa1b5mr3355911f8f.5.1777540362054; Thu, 30 Apr 2026 02:12:42 -0700 (PDT) Date: Thu, 30 Apr 2026 09:12:41 +0000 In-Reply-To: <20260427221155.2144848-2-dakr@kernel.org> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260427221155.2144848-1-dakr@kernel.org> <20260427221155.2144848-2-dakr@kernel.org> Message-ID: Subject: Re: [PATCH 01/24] rust: driver core: drop drvdata before devres release From: Alice Ryhl To: Danilo Krummrich Cc: gregkh@linuxfoundation.org, rafael@kernel.org, acourbot@nvidia.com, david.m.ertman@intel.com, ira.weiny@intel.com, leon@kernel.org, viresh.kumar@linaro.org, m.wilczynski@samsung.com, ukleinek@kernel.org, bhelgaas@google.com, kwilczynski@kernel.org, abdiel.janulgue@gmail.com, robin.murphy@arm.com, markus.probst@posteo.de, ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, nova-gpu@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-pm@vger.kernel.org, linux-pwm@vger.kernel.org, linux-pci@vger.kernel.org, rust-for-linux@vger.kernel.org Content-Type: text/plain; charset="utf-8" On Tue, Apr 28, 2026 at 12:10:59AM +0200, Danilo Krummrich wrote: > Move the post_unbind_rust callback before devres_release_all() in > device_unbind_cleanup(). > > With drvdata() removed, the driver's bus device private data is only > accessible by the owning driver itself. It is hence safe to drop the > driver's bus device private data before devres actions are released. > > This reordering is the key enabler for Higher-Ranked Lifetime Types > (HRT) in Rust device drivers -- it allows driver structs to hold direct > references to devres-managed resources, because the bus device private > data (and with it all such references) is guaranteed to be dropped while > the underlying devres resources are still alive. > > Without this change, devres resources would be freed first, leaving the > driver's bus device private data with dangling references during its > destructor. > > Signed-off-by: Danilo Krummrich > --- > drivers/base/dd.c | 2 +- > include/linux/device/driver.h | 4 ++-- > rust/kernel/driver.rs | 4 ++-- > 3 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 5799a60fd058..be59d2e13a15 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -593,9 +593,9 @@ static DEVICE_ATTR_RW(state_synced); > > static void device_unbind_cleanup(struct device *dev) > { > - devres_release_all(dev); > if (dev->driver->p_cb.post_unbind_rust) > dev->driver->p_cb.post_unbind_rust(dev); > + devres_release_all(dev); > arch_teardown_dma_ops(dev); > kfree(dev->dma_range_map); > dev->dma_range_map = NULL; I seem to recall that we discussed a plan to have two classes of devres callbacks where device unbind proceeds as follows: 1. Run first class of devres callbacks. 2. Device is now considered unbound. 3. Run second class of devres callbacks. Is that still the plan? Alice