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ANDROID: rust_binder: access lru list through private data

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When changing Rust Binder to use the new alloc_shrinker(), the layout
was changed so that lru_list is no longer stored next to the shrinker
object, but some shrinker callbacks were not updated to reflect that.
Thus, access the lru list through the shrinker's private data pointer,
instead of using a container_of operation.

Bug: 424727800
Change-Id: Iac09b2d81e555c3554101231de701dfa79b0e644
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
This commit is contained in:
Alice Ryhl
2025-06-13 11:29:25 +00:00
parent cf1ef61244
commit a7c066a30e
1 changed files with 7 additions and 8 deletions
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15
drivers/android/binder/page_range.rs
View File

@@ -93,6 +93,7 @@ impl Shrinker {
unsafe {
ptr::addr_of_mut!((*shrinker).count_objects).write(Some(rust_shrink_count));
ptr::addr_of_mut!((*shrinker).scan_objects).write(Some(rust_shrink_scan));
ptr::addr_of_mut!((*shrinker).private_data).write(self.list_lru.get().cast());
}
// SAFETY: The new shrinker has been fully initialized, so we can register it.
@@ -655,11 +656,10 @@ unsafe extern "C" fn rust_shrink_count(
shrink: *mut bindings::shrinker,
_sc: *mut bindings::shrink_control,
) -> c_ulong {
// SAFETY: This method is only used with the `Shrinker` type, and the cast is valid since
// `shrinker` is the first field of a #[repr(C)] struct.
let shrinker = unsafe { &*shrink.cast::<Shrinker>() };
// SAFETY: We can access our own private data.
let list_lru = unsafe { (*shrink).private_data.cast::<bindings::list_lru>() };
// SAFETY: Accessing the lru list is okay. Just an FFI call.
unsafe { bindings::list_lru_count(shrinker.list_lru.get()) }
unsafe { bindings::list_lru_count(list_lru) }
}
#[no_mangle]
@@ -667,9 +667,8 @@ unsafe extern "C" fn rust_shrink_scan(
shrink: *mut bindings::shrinker,
sc: *mut bindings::shrink_control,
) -> c_ulong {
// SAFETY: This method is only used with the `Shrinker` type, and the cast is valid since
// `shrinker` is the first field of a #[repr(C)] struct.
let shrinker = unsafe { &*shrink.cast::<Shrinker>() };
// SAFETY: We can access our own private data.
let list_lru = unsafe { (*shrink).private_data.cast::<bindings::list_lru>() };
// SAFETY: Caller guarantees that it is safe to read this field.
let nr_to_scan = unsafe { (*sc).nr_to_scan };
// SAFETY: Accessing the lru list is okay. Just an FFI call.
@@ -684,7 +683,7 @@ unsafe extern "C" fn rust_shrink_scan(
}
bindings::list_lru_walk(
shrinker.list_lru.get(),
list_lru,
Some(rust_shrink_free_page_wrap),
ptr::null_mut(),
nr_to_scan,