Message-ID: <20240704170738.3621-7-dakr@redhat.com>
Date: Thu,  4 Jul 2024 19:06:34 +0200
From: Danilo Krummrich <dakr@...hat.com>
To: ojeda@...nel.org,
	alex.gaynor@...il.com,
	wedsonaf@...il.com,
	boqun.feng@...il.com,
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Cc: daniel.almeida@...labora.com,
	faith.ekstrand@...labora.com,
	boris.brezillon@...labora.com,
	lina@...hilina.net,
	mcanal@...lia.com,
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	linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org,
	Danilo Krummrich <dakr@...hat.com>
Subject: [PATCH 06/20] rust: alloc: remove `krealloc_aligned`

Now that we have `Allocator` for `Kmalloc` in place, remove explicit
calls to `krealloc_aligned` and get rid of `krealloc_aligned` itself.

`bindings::krealloc` should only be called from `Kmalloc::realloc`.

Signed-off-by: Danilo Krummrich <dakr@...hat.com>
---
 rust/kernel/alloc/allocator.rs | 21 ---------------------
 rust/kernel/alloc/box_ext.rs   | 13 ++++---------
 rust/kernel/alloc/vec_ext.rs   | 23 +++++++++++++----------
 3 files changed, 17 insertions(+), 40 deletions(-)

diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index b7c0490f6415..1860cb79b875 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -36,27 +36,6 @@ fn aligned_size(new_layout: Layout) -> usize {
     size
 }
 
-/// Calls `krealloc` with a proper size to alloc a new object.
-///
-/// # Safety
-///
-/// - `ptr` can be either null or a pointer which has been allocated by this allocator.
-/// - `new_layout` must have a non-zero size.
-pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
-    // SAFETY:
-    // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
-    //   function safety requirement.
-    // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
-    //   according to the function safety requirement) or a result from `next_power_of_two()`.
-    unsafe {
-        bindings::krealloc(
-            ptr as *const core::ffi::c_void,
-            aligned_size(new_layout),
-            flags.0,
-        ) as *mut u8
-    }
-}
-
 unsafe impl Allocator for Kmalloc {
     unsafe fn realloc(
         &self,
diff --git a/rust/kernel/alloc/box_ext.rs b/rust/kernel/alloc/box_ext.rs
index 829cb1c1cf9e..1aeae02c147e 100644
--- a/rust/kernel/alloc/box_ext.rs
+++ b/rust/kernel/alloc/box_ext.rs
@@ -33,24 +33,19 @@ fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
     #[cfg(not(any(test, testlib)))]
     fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
         let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 {
-            core::ptr::NonNull::<_>::dangling().as_ptr()
+            core::ptr::NonNull::dangling()
         } else {
+            let alloc: &dyn super::Allocator = &super::allocator::Kmalloc;
             let layout = core::alloc::Layout::new::<MaybeUninit<T>>();
 
             // SAFETY: Memory is being allocated (first arg is null). The only other source of
             // safety issues is sleeping on atomic context, which is addressed by klint. Lastly,
             // the type is not a SZT (checked above).
-            let ptr =
-                unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) };
-            if ptr.is_null() {
-                return Err(AllocError);
-            }
-
-            ptr.cast::<MaybeUninit<T>>()
+            alloc.alloc(layout, flags)?.cast()
         };
 
         // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
         // zero-sized types, we use `NonNull::dangling`.
-        Ok(unsafe { Box::from_raw(ptr) })
+        Ok(unsafe { Box::from_raw(ptr.as_ptr()) })
     }
 }
diff --git a/rust/kernel/alloc/vec_ext.rs b/rust/kernel/alloc/vec_ext.rs
index e9a81052728a..bf277976ed38 100644
--- a/rust/kernel/alloc/vec_ext.rs
+++ b/rust/kernel/alloc/vec_ext.rs
@@ -118,6 +118,7 @@ fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError
 
     #[cfg(not(any(test, testlib)))]
     fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
+        let alloc: &dyn super::Allocator = &super::allocator::Kmalloc;
         let len = self.len();
         let cap = self.capacity();
 
@@ -145,16 +146,18 @@ fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>
 
         // SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to
         // `krealloc_aligned`. We also verified that the type is not a ZST.
-        let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags) };
-        if new_ptr.is_null() {
-            // SAFETY: We are just rebuilding the existing `Vec` with no changes.
-            unsafe { rebuild(self, old_ptr, len, cap) };
-            Err(AllocError)
-        } else {
-            // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap
-            // is greater than `cap`, so it continues to be >= `len`.
-            unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };
-            Ok(())
+        match unsafe { alloc.realloc(ptr.cast(), cap, layout, flags) } {
+            Ok(ptr) => {
+                // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements.
+                // `new_cap` is greater than `cap`, so it continues to be >= `len`.
+                unsafe { rebuild(self, ptr.as_ptr().cast(), len, new_cap) };
+                Ok(())
+            }
+            Err(err) => {
+                // SAFETY: We are just rebuilding the existing `Vec` with no changes.
+                unsafe { rebuild(self, old_ptr, len, cap) };
+                Err(err)
+            }
         }
     }
 }
-- 
2.45.2

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