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a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=1873; i=aliceryhl@google.com; h=from:subject:message-id; bh=3tfYucmdrXplIUc4VSHw+JRcor66PuJ268AQJ8tOuVo=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBoB2bffPl/slSxUpzd0wNgPhj4xxtJEPm1Wm/zU q5dJ6NJjKWJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCaAdm3wAKCRAEWL7uWMY5 RmmYD/0bypuWyiDN9HHeI0cxu3nrZoy/Lv53uCNMAo1Fl5eIKT/y/Q2dahESfTC2L/yF4kvun2Y G1spyLAUSAcAuot4RTn/CB5AWtwcBUxLVuCNFKSLtXG1LWqT7cwQqnFvOzHKxkgHmZkUyXMNtNz 61yPX9qV8eiZICiZV63HInfZ3jR0rX/fm4Qqz3WhTLibf1AVyHCJvEH/7ZFTxVzZvWRSUCBCytY KIvxxeVz8MCuUpZWvYylJIjj+jveYdC3d6qkbxfMnDYip1lRzZ1qUqAT+AdGPJ92Za9z6UxU4IE 0DgemFV3ghTTYmYt+WO1GQdMfMpDZiAtizZsfMOWhvaNaOvjKbzXZwOIXnqcE1aIjxKFaTu0JPJ 0zH4nDdn0GsBdNyCGEppKZJwbNraCl8PHHqUbHz9Uvvi9B3YMGxHGhxoZ3WlV/XDHekL340vrRW go0vWFQQddC2371LpQv2PNILrew0JF8aprM76/R60E+NG/NUV+j/QH6kx7TxY6PW+AZ/KjeN6wF cWecG42rhI+w5cGyuqpF38HXMi1BMaFcFCIDIuvGaPcdDb+J+N2b2Sjiq9lPIo9AY0a9Gpi2To+ i0LeaY43ZVy9w6Vs8uwwZtJNU/Dgfbfw/aH2YuLR9dLXJBK0AQAuE22OwnvwXvWKGQ/C7cJpc1I /xYpN/9KQDzzK6Q== X-Mailer: b4 0.14.2 Message-ID: <20250422-vec-methods-v3-2-deff5eea568a@google.com> Subject: [PATCH v3 2/7] rust: alloc: add Vec::pop From: Alice Ryhl To: Danilo Krummrich Cc: Matthew Maurer , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl Content-Type: text/plain; charset="utf-8" This introduces a basic method that our custom Vec is missing. I expect that it will be used in many places, but at the time of writing, Rust Binder has six calls to Vec::pop. Signed-off-by: Alice Ryhl --- rust/kernel/alloc/kvec.rs | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 412a2fe3ce79a0681175bf358e8e0f628e77e875..ebca0cfd31c67f3ce13c4825d7039e34bb54f4d4 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -320,6 +320,37 @@ pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> { Ok(()) } + /// Removes the last element from a vector and returns it, or `None` if it is empty. + /// + /// # Examples + /// + /// ``` + /// let mut v = KVec::new(); + /// v.push(1, GFP_KERNEL)?; + /// v.push(2, GFP_KERNEL)?; + /// assert_eq!(&v, &[1, 2]); + /// + /// assert_eq!(v.pop(), Some(2)); + /// assert_eq!(v.pop(), Some(1)); + /// assert_eq!(v.pop(), None); + /// # Ok::<(), Error>(()) + /// ``` + pub fn pop(&mut self) -> Option { + if self.is_empty() { + return None; + } + + let removed: *mut T = { + // SAFETY: We just checked that the length is at least one. + let slice = unsafe { self.dec_len(1) }; + // SAFETY: The argument to `dec_len` was 1 so this returns a slice of length 1. + unsafe { slice.get_unchecked_mut(0) } + }; + + // SAFETY: The guarantees of `dec_len` allow us to take ownership of this value. + Some(unsafe { removed.read() }) + } + /// Creates a new [`Vec`] instance with at least the given capacity. /// /// # Examples -- 2.49.0.805.g082f7c87e0-goog