On Fri, Mar 14, 2025 at 09:42:33PM -0500, Andrew Ballance wrote: > implements the equivalent to the std's Vec::truncate > on the kernel's Vec type. > > Signed-off-by: Andrew Ballance <andrewjballance@xxxxxxxxx> > --- > rust/kernel/alloc/kvec.rs | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs > index ae9d072741ce..75e9feebb81f 100644 > --- a/rust/kernel/alloc/kvec.rs > +++ b/rust/kernel/alloc/kvec.rs > @@ -452,6 +452,42 @@ pub fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocEr > > Ok(()) > } > + > + /// Shortens the vector, setting the length to `len` and drops the removed values. > + /// If `len` is greater than or equal to the current length, this does nothing. > + /// > + /// This has no effect on the capacity and will not allocate. Nit: Please also add an empty line here. > + /// # Examples > + /// ``` > + /// let mut v = kernel::kvec![1, 2, 3]?; > + /// v.truncate(1); > + /// assert_eq!(v.len(), 1); > + /// assert_eq!(&v, &[1]); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + pub fn truncate(&mut self, len: usize) { > + if len >= self.len() { > + return; > + } > + > + // [new_len, len) is guaranteed to be valid because [0, len) is guaranteed to be valid We typically use markdown for comments. > + let drop_range = len..self.len(); > + > + // SAFETY: > + // we can safely ignore the bounds check because we already did our own check > + let ptr: *mut [T] = unsafe { self.get_unchecked_mut(drop_range) }; > + > + // SAFETY: > + // it is safe to shrink the length because the new length is > + // guaranteed to be less than the old length > + unsafe { self.set_len(len) }; I just sent out a fix [1] for the safety requirements of set_len() in [1], which I think would be good to consider. [1] https://lore.kernel.org/rust-for-linux/20250315154436.65065-1-dakr@xxxxxxxxxx/