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Sat, 13 Sep 2025 01:11:11 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHdW6vjLv1klGa8RwK/ePRw1iW92Mp6y60bQ215floaRcdsRhXbiyNCPl9Qzxnp9p/UCgn/MQ== X-Received: by 2002:a05:600c:1f8c:b0:45b:64bc:56ea with SMTP id 5b1f17b1804b1-45f211f8841mr45993515e9.23.1757751071320; Sat, 13 Sep 2025 01:11:11 -0700 (PDT) Received: from [192.168.10.48] ([151.95.56.250]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45e017b4222sm93435625e9.20.2025.09.13.01.11.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 13 Sep 2025 01:11:09 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Zhao Liu Subject: [PULL 30/61] rust: remove unused global qemu "allocator" Date: Sat, 13 Sep 2025 10:09:11 +0200 Message-ID: <20250913080943.11710-31-pbonzini@redhat.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250913080943.11710-1-pbonzini@redhat.com> References: <20250913080943.11710-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Marc-André Lureau The global allocator has always been disabled. There is no clear reason Rust and C should use the same allocator. Allocations made from Rust must be freed by Rust, and same for C, otherwise we head into troubles. Signed-off-by: Marc-André Lureau Link: https://lore.kernel.org/r/20250827104147.717203-3-marcandre.lureau@redhat.com Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- meson.build | 4 -- rust/Cargo.toml | 2 +- rust/qemu-api/Cargo.toml | 1 - rust/qemu-api/meson.build | 1 - rust/qemu-api/src/lib.rs | 135 -------------------------------------- 5 files changed, 1 insertion(+), 142 deletions(-) diff --git a/meson.build b/meson.build index a238df3f5e3..6ade30f36ad 100644 --- a/meson.build +++ b/meson.build @@ -1086,9 +1086,6 @@ glib = declare_dependency(dependencies: [glib_pc, gmodule], # TODO: remove this check and the corresponding workaround (qtree) when # the minimum supported glib is >= 2.75.3 glib_has_gslice = glib.version().version_compare('<2.75.3') -# Check whether glib has the aligned_alloc family of functions. -# -glib_has_aligned_alloc = glib.version().version_compare('>=2.72.0') # override glib dep to include the above refinements meson.override_dependency('glib-2.0', glib) @@ -2702,7 +2699,6 @@ config_host_data.set('CONFIG_GETLOADAVG', cc.has_function('getloadavg')) config_host_data.set('HAVE_COPY_FILE_RANGE', cc.has_function('copy_file_range')) config_host_data.set('HAVE_GETIFADDRS', cc.has_function('getifaddrs')) config_host_data.set('HAVE_GLIB_WITH_SLICE_ALLOCATOR', glib_has_gslice) -config_host_data.set('HAVE_GLIB_WITH_ALIGNED_ALLOC', glib_has_aligned_alloc) config_host_data.set('HAVE_OPENPTY', cc.has_function('openpty', dependencies: util)) config_host_data.set('HAVE_STRCHRNUL', cc.has_function('strchrnul', prefix: osdep_prefix)) config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system', prefix: '#include ')) diff --git a/rust/Cargo.toml b/rust/Cargo.toml index 9b26aa07cec..d98d2b77026 100644 --- a/rust/Cargo.toml +++ b/rust/Cargo.toml @@ -23,7 +23,7 @@ libc = "0.2.162" [workspace.lints.rust] unexpected_cfgs = { level = "deny", check-cfg = [ - 'cfg(MESON)', 'cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)', + 'cfg(MESON)', ] } # Occasionally, we may need to silence warnings and clippy lints that diff --git a/rust/qemu-api/Cargo.toml b/rust/qemu-api/Cargo.toml index c07a17a28b0..c5ed78035b6 100644 --- a/rust/qemu-api/Cargo.toml +++ b/rust/qemu-api/Cargo.toml @@ -21,7 +21,6 @@ libc = { workspace = true } [features] default = ["debug_cell"] -allocator = [] debug_cell = [] [lints] diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index a090297c458..062009f1618 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -2,7 +2,6 @@ _qemu_api_cfg = run_command(rustc_args, '--config-headers', config_host_h, '--features', files('Cargo.toml'), capture: true, check: true).stdout().strip().splitlines() -# _qemu_api_cfg += ['--cfg', 'feature="allocator"'] if get_option('debug_mutex') _qemu_api_cfg += ['--cfg', 'feature="debug_cell"'] endif diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index bcb51c7986a..daa2493bb69 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -36,139 +36,4 @@ // crate). extern crate self as qemu_api; -use std::{ - alloc::{GlobalAlloc, Layout}, - ffi::c_void, -}; - pub use error::{Error, Result}; - -#[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] -extern "C" { - fn g_aligned_alloc0( - n_blocks: bindings::gsize, - n_block_bytes: bindings::gsize, - alignment: bindings::gsize, - ) -> bindings::gpointer; - fn g_aligned_free(mem: bindings::gpointer); -} - -#[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] -extern "C" { - fn qemu_memalign(alignment: usize, size: usize) -> *mut c_void; - fn qemu_vfree(ptr: *mut c_void); -} - -extern "C" { - fn g_malloc0(n_bytes: bindings::gsize) -> bindings::gpointer; - fn g_free(mem: bindings::gpointer); -} - -/// An allocator that uses the same allocator as QEMU in C. -/// -/// It is enabled by default with the `allocator` feature. -/// -/// To set it up manually as a global allocator in your crate: -/// -/// ```ignore -/// use qemu_api::QemuAllocator; -/// -/// #[global_allocator] -/// static GLOBAL: QemuAllocator = QemuAllocator::new(); -/// ``` -#[derive(Clone, Copy, Debug)] -#[repr(C)] -pub struct QemuAllocator { - _unused: [u8; 0], -} - -#[cfg_attr(all(feature = "allocator", not(test)), global_allocator)] -pub static GLOBAL: QemuAllocator = QemuAllocator::new(); - -impl QemuAllocator { - // From the glibc documentation, on GNU systems, malloc guarantees 16-byte - // alignment on 64-bit systems and 8-byte alignment on 32-bit systems. See - // https://www.gnu.org/software/libc/manual/html_node/Malloc-Examples.html. - // This alignment guarantee also applies to Windows and Android. On Darwin - // and OpenBSD, the alignment is 16 bytes on both 64-bit and 32-bit systems. - #[cfg(all( - target_pointer_width = "32", - not(any(target_os = "macos", target_os = "openbsd")) - ))] - pub const DEFAULT_ALIGNMENT_BYTES: Option = Some(8); - #[cfg(all( - target_pointer_width = "64", - not(any(target_os = "macos", target_os = "openbsd")) - ))] - pub const DEFAULT_ALIGNMENT_BYTES: Option = Some(16); - #[cfg(all( - any(target_pointer_width = "32", target_pointer_width = "64"), - any(target_os = "macos", target_os = "openbsd") - ))] - pub const DEFAULT_ALIGNMENT_BYTES: Option = Some(16); - #[cfg(not(any(target_pointer_width = "32", target_pointer_width = "64")))] - pub const DEFAULT_ALIGNMENT_BYTES: Option = None; - - pub const fn new() -> Self { - Self { _unused: [] } - } -} - -impl Default for QemuAllocator { - fn default() -> Self { - Self::new() - } -} - -// Sanity check. -const _: [(); 8] = [(); ::core::mem::size_of::<*mut c_void>()]; - -unsafe impl GlobalAlloc for QemuAllocator { - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - if matches!(Self::DEFAULT_ALIGNMENT_BYTES, Some(default) if default.checked_rem(layout.align()) == Some(0)) - { - // SAFETY: g_malloc0() is safe to call. - unsafe { g_malloc0(layout.size().try_into().unwrap()).cast::() } - } else { - #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] - { - // SAFETY: g_aligned_alloc0() is safe to call. - unsafe { - g_aligned_alloc0( - layout.size().try_into().unwrap(), - 1, - layout.align().try_into().unwrap(), - ) - .cast::() - } - } - #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] - { - // SAFETY: qemu_memalign() is safe to call. - unsafe { qemu_memalign(layout.align(), layout.size()).cast::() } - } - } - } - - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - if matches!(Self::DEFAULT_ALIGNMENT_BYTES, Some(default) if default.checked_rem(layout.align()) == Some(0)) - { - // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid - // glib-allocated pointer, so `g_free`ing is safe. - unsafe { g_free(ptr.cast::<_>()) } - } else { - #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)] - { - // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid aligned - // glib-allocated pointer, so `g_aligned_free`ing is safe. - unsafe { g_aligned_free(ptr.cast::<_>()) } - } - #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))] - { - // SAFETY: `ptr` must have been allocated by Self::alloc thus a valid aligned - // glib-allocated pointer, so `qemu_vfree`ing is safe. - unsafe { qemu_vfree(ptr.cast::<_>()) } - } - } - } -} -- 2.51.0