While there are default impls for these methods, using the respective C
api's is faster. Currently neither the existing nor these new
GlobalAlloc method implementations are actually called. Instead the
__rust_* function defined below the GlobalAlloc impl are used. With
rustc 1.71 these functions will be gone and all allocation calls will go
through the GlobalAlloc implementation.
Link: https://github.com/Rust-for-Linux/linux/issues/68
Signed-off-by: Björn Roy Baron <[email protected]>
[boqun: add size adjustment for alignment requirement]
Signed-off-by: Boqun Feng <[email protected]>
---
Miguel, I fold my diff into Björn's original patch and make a v2, it
relies on the other patch:
https://lore.kernel.org/rust-for-linux/[email protected]/
So this v2 (if all goes well) is targeted for v6.6, JFYI.
v1 -> v2:
* Add size adjustment for align requirement.
rust/kernel/allocator.rs | 59 ++++++++++++++++++++++++++++++++++++----
1 file changed, 54 insertions(+), 5 deletions(-)
diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index 66575cf87ce2..af723c2924dc 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/allocator.rs
@@ -9,8 +9,17 @@
struct KernelAllocator;
-unsafe impl GlobalAlloc for KernelAllocator {
- unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+impl KernelAllocator {
+ /// # Safety
+ ///
+ /// * `ptr` can be either null or a pointer which has been allocated by this allocator.
+ /// * `layout` must have a non-zero size.
+ unsafe fn krealloc_with_flags(
+ &self,
+ ptr: *mut u8,
+ layout: Layout,
+ flags: bindings::gfp_t,
+ ) -> *mut u8 {
// Customized layouts from `Layout::from_size_align()` can have size < align, so pads first.
let layout = layout.pad_to_align();
@@ -26,9 +35,22 @@ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
size = size.next_power_of_two();
}
- // `krealloc()` is used instead of `kmalloc()` because the latter is
- // an inline function and cannot be bound to as a result.
- unsafe { bindings::krealloc(ptr::null(), size, bindings::GFP_KERNEL) as *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, size, flags) as *mut u8 }
+ }
+}
+
+unsafe impl GlobalAlloc for KernelAllocator {
+ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+ // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
+ // requirement.
+ unsafe { self.krealloc_with_flags(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
}
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
@@ -36,6 +58,33 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
bindings::kfree(ptr as *const core::ffi::c_void);
}
}
+
+ unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+ // SAFETY:
+ // * `new_size` when rounded up to the nearest multiple of `layout.align()`, will not
+ // overflow `isize` by the function safety requirement.
+ // * `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
+ let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
+
+ // SAFETY:
+ // * `ptr` is either null or a pointer allocated by this allocator by function safety
+ // requirement.
+ // * the size of `layout` is not zero because `new_size` is not zero by function safety
+ // requirement.
+ unsafe { self.krealloc_with_flags(ptr, layout, bindings::GFP_KERNEL) }
+ }
+
+ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+ // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
+ // requirement.
+ unsafe {
+ self.krealloc_with_flags(
+ ptr::null_mut(),
+ layout,
+ bindings::GFP_KERNEL | bindings::__GFP_ZERO,
+ )
+ }
+ }
}
#[global_allocator]
--
2.39.2
On 6/25/23 20:25, Boqun Feng wrote:
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
> Signed-off-by: Björn Roy Baron <[email protected]>
> [boqun: add size adjustment for alignment requirement]
I think that this should go above Link and Signed-off-bys, although I'm
not sure if maintainers do it when is merged.
> Signed-off-by: Boqun Feng <[email protected]>
> ---
> Miguel, I fold my diff into Björn's original patch and make a v2, it
> relies on the other patch:
>
> https://lore.kernel.org/rust-for-linux/[email protected]/
>
> So this v2 (if all goes well) is targeted for v6.6, JFYI.
>
> v1 -> v2:
>
> * Add size adjustment for align requirement.
>
> [...]
Newbie question, aren't tabs in the commit message verboten?
Aside from those two nits everything else LGTM.
Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
On Mon, Jun 26, 2023 at 5:34 AM Martin Rodriguez Reboredo
<[email protected]> wrote:
>
> I think that this should go above Link and Signed-off-bys, although I'm
> not sure if maintainers do it when is merged.
Both styles are used, it is fine either way. Personally, I pick one or
the other depending on the kind of comment.
Having said that, there seems to be a missing `From:`, but I can fix
that on my side if Björn is the intended author.
> Newbie question, aren't tabs in the commit message verboten?
I am not aware of such a rule, and there are commits in the kernel
with tabs, e.g. commit 9828ed3f695a ("module: error out early on
concurrent load of the same module file").
In any case, that text doesn't go into the commit message, because it
is after the `---` line.
Cheers,
Miguel
On 6/26/23 06:40, Miguel Ojeda wrote:
> On Mon, Jun 26, 2023 at 5:34 AM Martin Rodriguez Reboredo
> <[email protected]> wrote:
>>
>> I think that this should go above Link and Signed-off-bys, although I'm
>> not sure if maintainers do it when is merged.
>
> Both styles are used, it is fine either way. Personally, I pick one or
> the other depending on the kind of comment.
>
> Having said that, there seems to be a missing `From:`, but I can fix
> that on my side if Björn is the intended author.
>
>> Newbie question, aren't tabs in the commit message verboten?
>
> I am not aware of such a rule, and there are commits in the kernel
> with tabs, e.g. commit 9828ed3f695a ("module: error out early on
> concurrent load of the same module file").
>
> In any case, that text doesn't go into the commit message, because it
> is after the `---` line.
>
> Cheers,
> Miguel
Alrighty, both make sense to me, thanks for the explanations!
-> Martin
On 26.06.23 01:25, Boqun Feng wrote:
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
> Signed-off-by: Björn Roy Baron <[email protected]>
> [boqun: add size adjustment for alignment requirement]
> Signed-off-by: Boqun Feng <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
> ---
> Miguel, I fold my diff into Björn's original patch and make a v2, it
> relies on the other patch:
>
> https://lore.kernel.org/rust-for-linux/[email protected]/
>
> So this v2 (if all goes well) is targeted for v6.6, JFYI.
>
> v1 -> v2:
>
> * Add size adjustment for align requirement.
>
> rust/kernel/allocator.rs | 59 ++++++++++++++++++++++++++++++++++++----
> 1 file changed, 54 insertions(+), 5 deletions(-)
>
> diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
> index 66575cf87ce2..af723c2924dc 100644
> --- a/rust/kernel/allocator.rs
> +++ b/rust/kernel/allocator.rs
> @@ -9,8 +9,17 @@
>
> struct KernelAllocator;
>
> -unsafe impl GlobalAlloc for KernelAllocator {
> - unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> +impl KernelAllocator {
> + /// # Safety
> + ///
> + /// * `ptr` can be either null or a pointer which has been allocated by this allocator.
> + /// * `layout` must have a non-zero size.
> + unsafe fn krealloc_with_flags(
> + &self,
> + ptr: *mut u8,
> + layout: Layout,
> + flags: bindings::gfp_t,
> + ) -> *mut u8 {
> // Customized layouts from `Layout::from_size_align()` can have size < align, so pads first.
> let layout = layout.pad_to_align();
>
> @@ -26,9 +35,22 @@ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> size = size.next_power_of_two();
> }
>
> - // `krealloc()` is used instead of `kmalloc()` because the latter is
> - // an inline function and cannot be bound to as a result.
> - unsafe { bindings::krealloc(ptr::null(), size, bindings::GFP_KERNEL) as *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, size, flags) as *mut u8 }
> + }
> +}
> +
> +unsafe impl GlobalAlloc for KernelAllocator {
> + unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
> }
>
> unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> @@ -36,6 +58,33 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> bindings::kfree(ptr as *const core::ffi::c_void);
> }
> }
> +
> + unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
> + // SAFETY:
> + // * `new_size` when rounded up to the nearest multiple of `layout.align()`, will not
> + // overflow `isize` by the function safety requirement.
> + // * `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
> + let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
> +
> + // SAFETY:
> + // * `ptr` is either null or a pointer allocated by this allocator by function safety
> + // requirement.
> + // * the size of `layout` is not zero because `new_size` is not zero by function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr, layout, bindings::GFP_KERNEL) }
> + }
> +
> + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> + unsafe {
> + self.krealloc_with_flags(
> + ptr::null_mut(),
> + layout,
> + bindings::GFP_KERNEL | bindings::__GFP_ZERO,
> + )
> + }
> + }
> }
>
> #[global_allocator]
> --
> 2.39.2
>
On Sun, 25 Jun 2023 16:25:28 -0700
Boqun Feng <[email protected]> wrote:
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
> Signed-off-by: Björn Roy Baron <[email protected]>
> [boqun: add size adjustment for alignment requirement]
> Signed-off-by: Boqun Feng <[email protected]>
Reviewed-by: Gary Guo <[email protected]>
> ---
> Miguel, I fold my diff into Björn's original patch and make a v2, it
> relies on the other patch:
>
> https://lore.kernel.org/rust-for-linux/[email protected]/
>
> So this v2 (if all goes well) is targeted for v6.6, JFYI.
>
> v1 -> v2:
>
> * Add size adjustment for align requirement.
>
> rust/kernel/allocator.rs | 59 ++++++++++++++++++++++++++++++++++++----
> 1 file changed, 54 insertions(+), 5 deletions(-)
>
> diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
> index 66575cf87ce2..af723c2924dc 100644
> --- a/rust/kernel/allocator.rs
> +++ b/rust/kernel/allocator.rs
> @@ -9,8 +9,17 @@
>
> struct KernelAllocator;
>
> -unsafe impl GlobalAlloc for KernelAllocator {
> - unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> +impl KernelAllocator {
> + /// # Safety
> + ///
> + /// * `ptr` can be either null or a pointer which has been allocated by this allocator.
> + /// * `layout` must have a non-zero size.
> + unsafe fn krealloc_with_flags(
> + &self,
> + ptr: *mut u8,
> + layout: Layout,
> + flags: bindings::gfp_t,
> + ) -> *mut u8 {
> // Customized layouts from `Layout::from_size_align()` can have size < align, so pads first.
> let layout = layout.pad_to_align();
>
> @@ -26,9 +35,22 @@ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> size = size.next_power_of_two();
> }
>
> - // `krealloc()` is used instead of `kmalloc()` because the latter is
> - // an inline function and cannot be bound to as a result.
> - unsafe { bindings::krealloc(ptr::null(), size, bindings::GFP_KERNEL) as *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, size, flags) as *mut u8 }
> + }
> +}
> +
> +unsafe impl GlobalAlloc for KernelAllocator {
> + unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
> }
>
> unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> @@ -36,6 +58,33 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> bindings::kfree(ptr as *const core::ffi::c_void);
> }
> }
> +
> + unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
> + // SAFETY:
> + // * `new_size` when rounded up to the nearest multiple of `layout.align()`, will not
> + // overflow `isize` by the function safety requirement.
> + // * `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
> + let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
> +
> + // SAFETY:
> + // * `ptr` is either null or a pointer allocated by this allocator by function safety
> + // requirement.
> + // * the size of `layout` is not zero because `new_size` is not zero by function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr, layout, bindings::GFP_KERNEL) }
> + }
> +
> + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> + unsafe {
> + self.krealloc_with_flags(
> + ptr::null_mut(),
> + layout,
> + bindings::GFP_KERNEL | bindings::__GFP_ZERO,
> + )
> + }
> + }
> }
>
> #[global_allocator]
On Mon, Jun 26, 2023 at 1:25 AM Boqun Feng <[email protected]> wrote:
>
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
> Signed-off-by: Björn Roy Baron <[email protected]>
> [boqun: add size adjustment for alignment requirement]
> Signed-off-by: Boqun Feng <[email protected]>
Applied to `rust-next`, thanks! I will use it as a base for the 1.71 upgrade.
Cheers,
Miguel