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2025-06-22rust: enable `clippy::as_underscore` lintTamir Duberstein
In Rust 1.63.0, Clippy introduced the `as_underscore` lint [1]: > The conversion might include lossy conversion or a dangerous cast that > might go undetected due to the type being inferred. > > The lint is allowed by default as using `_` is less wordy than always > specifying the type. Always specifying the type is especially helpful in function call contexts where the inferred type may change at a distance. Specifying the type also allows Clippy to spot more cases of `useless_conversion`. The primary downside is the need to specify the type in trivial getters. There are 4 such functions: 3 have become slightly less ergonomic, 1 was revealed to be a `useless_conversion`. While this doesn't eliminate unchecked `as` conversions, it makes such conversions easier to scrutinize. It also has the slight benefit of removing a degree of freedom on which to bikeshed. Thus apply the changes and enable the lint -- no functional change intended. Link: https://rust-lang.github.io/rust-clippy/master/index.html#as_underscore [1] Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Tamir Duberstein <tamird@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-4-f43b024581e8@gmail.com [ Changed `isize` to `c_long`. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-11mm: rust: add VmaNew for f_ops->mmap()Alice Ryhl
This type will be used when setting up a new vma in an f_ops->mmap() hook. Using a separate type from VmaRef allows us to have a separate set of operations that you are only able to use during the mmap() hook. For example, the VM_MIXEDMAP flag must not be changed after the initial setup that happens during the f_ops->mmap() hook. To avoid setting invalid flag values, the methods for clearing VM_MAYWRITE and similar involve a check of VM_WRITE, and return an error if VM_WRITE is set. Trying to use `try_clear_maywrite` without checking the return value results in a compilation error because the `Result` type is marked #[must_use]. For now, there's only a method for VM_MIXEDMAP and not VM_PFNMAP. When we add a VM_PFNMAP method, we will need some way to prevent you from setting both VM_MIXEDMAP and VM_PFNMAP on the same vma. Link: https://lkml.kernel.org/r/20250408-vma-v16-6-d8b446e885d9@google.com Signed-off-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Jann Horn <jannh@google.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Balbir Singh <balbirs@nvidia.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: Björn Roy Baron <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Gary Guo <gary@garyguo.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Trevor Gross <tmgross@umich.edu> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-11mm: rust: add vm_insert_pageAlice Ryhl
The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP flag, so we introduce a new type to keep track of such vmas. The approach used in this patch assumes that we will not need to encode many flag combinations in the type. I don't think we need to encode more than VM_MIXEDMAP and VM_PFNMAP as things are now. However, if that becomes necessary, using generic parameters in a single type would scale better as the number of flags increases. Link: https://lkml.kernel.org/r/20250408-vma-v16-3-d8b446e885d9@google.com Signed-off-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Balbir Singh <balbirs@nvidia.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: Björn Roy Baron <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Trevor Gross <tmgross@umich.edu> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-11mm: rust: add vm_area_struct methods that require read accessAlice Ryhl
This adds a type called VmaRef which is used when referencing a vma that you have read access to. Here, read access means that you hold either the mmap read lock or the vma read lock (or stronger). Additionally, a vma_lookup method is added to the mmap read guard, which enables you to obtain a &VmaRef in safe Rust code. This patch only provides a way to lock the mmap read lock, but a follow-up patch also provides a way to just lock the vma read lock. Link: https://lkml.kernel.org/r/20250408-vma-v16-2-d8b446e885d9@google.com Signed-off-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Jann Horn <jannh@google.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Balbir Singh <balbirs@nvidia.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: Björn Roy Baron <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Trevor Gross <tmgross@umich.edu> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>