Merge tag 'drm-rust-next-2025-11-18' of https://gitlab.freedesktop.org/drm/rust/kernel into drm-next

Cross-subsystem Changes:

Rust
  - Make slice::as_flattened usable on all supported versions of rustc.
  - Add FromBytes::from_bytes_prefix() method.

Core Changes:

  - Update Tyr in MAINTAINERS file.
  - Remove redundant device ptr from Rust GEM object.
  - Change how AlwaysRefCounted is implemented for GEM objects.
  - Add deferred vm_bo cleanup to GPUVM and use it in Panthor.

Driver Changes:

Nova Core
  - Introduction of bitfield! macro, with support for different storage sizes
    and custom visibility.
  - Introduction of safe converters between integer types for which the
    conversion is lossless.
  - GSP initialized up to fully booted state on Ampere.
  - Use more future-proof register for GPU identification.
  - Various simplifications and optimizations.

Nova
  - Select NOVA_CORE.
  - Depend on CONFIG_64BIT.

Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/aRxtJC0D1pQUepF4@google.com

1 files changed, 11 insertions, 22 deletions

diff --git a/drivers/gpu/nova-core/util.rs b/drivers/gpu/nova-core/util.rs
index bf35f00cb732..4b503249a3ef 100644
--- a/drivers/gpu/nova-core/util.rs
+++ b/drivers/gpu/nova-core/util.rs
@@ -1,27 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use kernel::prelude::*;
-use kernel::time::{Delta, Instant, Monotonic};
-
-/// Wait until `cond` is true or `timeout` elapsed.
-///
-/// When `cond` evaluates to `Some`, its return value is returned.
+/// Converts a null-terminated byte slice to a string, or `None` if the array does not
+/// contains any null byte or contains invalid characters.
 ///
-/// `Err(ETIMEDOUT)` is returned if `timeout` has been reached without `cond` evaluating to
-/// `Some`.
-///
-/// TODO[DLAY]: replace with `read_poll_timeout` once it is available.
-/// (https://lore.kernel.org/lkml/20250220070611.214262-8-fujita.tomonori@gmail.com/)
-pub(crate) fn wait_on<R, F: Fn() -> Option<R>>(timeout: Delta, cond: F) -> Result<R> {
-    let start_time = Instant::<Monotonic>::now();
-
-    loop {
-        if let Some(ret) = cond() {
-            return Ok(ret);
-        }
+/// Contrary to [`kernel::str::CStr::from_bytes_with_nul`], the null byte can be anywhere in the
+/// slice, and not only in the last position.
+pub(crate) fn str_from_null_terminated(bytes: &[u8]) -> Option<&str> {
+    use kernel::str::CStr;
 
-        if start_time.elapsed().as_nanos() > timeout.as_nanos() {
-            return Err(ETIMEDOUT);
-        }
-    }
+    bytes
+        .iter()
+        .position(|&b| b == 0)
+        .and_then(|null_pos| CStr::from_bytes_with_nul(&bytes[..=null_pos]).ok())
+        .and_then(|cstr| cstr.to_str().ok())
 }