[PATCH] rust: less allocation in CString::try_from
From: Onur Özkan <hidden>
Date: 2025-09-15 07:00:08
Also in:
lkml
Subsystem:
rust, the rest · Maintainers:
Miguel Ojeda, Linus Torvalds
Allocates buffer with the correct capacity upfront by using the length of the `CStr` to avoid extra and unnecessary re-allocation when converting from `CStr` to `CString`. Signed-off-by: Onur Özkan <redacted> --- rust/kernel/str.rs | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 6c892550c0ba..98d41d995e45 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs@@ -946,9 +946,10 @@ impl<'a> TryFrom<&'a CStr> for CString { type Error = AllocError; fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> { - let mut buf = KVec::new(); + let bytes = cstr.to_bytes_with_nul(); - buf.extend_from_slice(cstr.to_bytes_with_nul(), GFP_KERNEL)?; + let mut buf = KVec::with_capacity(bytes.len(), GFP_KERNEL)?; + buf.extend_from_slice(bytes, GFP_KERNEL)?; // INVARIANT: The `CStr` and `CString` types have the same invariants for // the string data, and we copied it over without changes. --
2.51.0