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a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=1965; i=aliceryhl@google.com; h=from:subject:message-id; bh=CenZwVOD+GrhyGqXr7eT4mqrBBg+m3/fOxMffAwc6YE=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBn3VcnRUiLDyS+/y9aPym1UGxnWYuFowsPTBhvo eunLeIjeqCJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZ91XJwAKCRAEWL7uWMY5 RuMrD/48ZEWJt7SecaUIQ6dxxdUbGuIINRB33Cj7n9VFJ0LeTrdZwvaKHenGsqt0DUe0ISCphQ9 NxRzT3Og/mJkCXL+V76PUg7g82LwLG4HqI+KcyS47ytPTozohC/jnT0k0aNzpyEDVV9G+MzOE2q woYoD8+NGDVlbb/BqP1jSGT+vMoCXCkaWRJn2yCbKd49GEqpYpI/1hRpRwhvC6PcaeS5+7IpcZ8 yG036eNtsM72oJTCUAo28fEffERRcXp5yqwq/zn/XSsUPXETtRFsJgIMwDFEQBF2xT9qHzN2sAM oJit/chN4q19jYRBylKecR79zYABtDFZO/qCzrbYM0c+5U4bll9TIFbQ8zut9jQMiNxEMYEgNgG 7r808ZAetZ/6jrRqqGq6iUeXlv9a/Mzzrvnj1nzgAReWK//J7RQxKsyJRxlIIj7hFXy5cGm1aa+ rP0qJoIqM9EF+fB7lBbJ6UiQLA/JVzZV2Xpp/XYtOvz/AfiTYIUWLEsI53Ozgoo6lhMlidDf9/V E7rsKXbeC8SAOcLF6KoFqqsg0/itVkNT1i976l0Kc+rUTPvNz13QuenjDK42MAl/8oLIbNb0NQV +mKm9+IuO3kaBGmmezdYbaAIg91j9QP2Y2U5GOPOcdeCZ2FJFN/g3pzDMX6fDZPyLCOQu1whnaM r384qMqhlA7u49A== X-Mailer: b4 0.14.2 Message-ID: <20250321-vec-methods-v2-3-6d9c8a4634cb@google.com> Subject: [PATCH v2 3/7] rust: alloc: add Vec::push_within_capacity From: Alice Ryhl To: Danilo Krummrich Cc: Matthew Maurer , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl , Benno Lossin Content-Type: text/plain; charset="utf-8" This introduces a new method called `push_within_capacity` for appending to a vector without attempting to allocate if the capacity is full. Rust Binder will use this in various places to safely push to a vector while holding a spinlock. The existing Vec::push method is reimplemented in terms of the new method. Reviewed-by: Benno Lossin Signed-off-by: Alice Ryhl --- rust/kernel/alloc/kvec.rs | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index e42c5c40c992c796409505da70975f970524fc24..c9de619466eed1590fda039a291207100729a96a 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -284,6 +284,31 @@ pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit] { /// ``` pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> { self.reserve(1, flags)?; + let err = self.push_within_capacity(v); + // SAFETY: The call to `reserve` was successful, so `push_within_capacity` cannot fail. + unsafe { err.unwrap_unchecked() }; + Ok(()) + } + + /// Appends an element to the back of the [`Vec`] instance. + /// + /// Fails if the vector does not have capacity for the new element. + /// + /// # Examples + /// + /// ``` + /// let mut v = KVec::with_capacity(10, GFP_KERNEL); + /// for i in 0..10 { + /// v.push_within_capacity(i).unwrap(); + /// } + /// + /// assert!(v.push_within_capacity(10).is_err()); + /// # Ok::<(), Error>(()) + /// ``` + pub fn push_within_capacity(&mut self, v: T) -> Result<(), T> { + if self.len() >= self.capacity() { + return Err(v); + } // SAFETY: // - `self.len` is smaller than `self.capacity` and hence, the resulting pointer is -- 2.49.0.395.g12beb8f557-goog