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Howlett" , Tamir Duberstein , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 4/4] rust: xarray: Add Guard::find() helper Date: Fri, 17 Apr 2026 11:28:35 +0300 Message-ID: <20260417082836.29530-1-work@onurozkan.dev> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20260417-tyr-ioctls-deps-v1-4-41c6e9bb061c@linux.dev> References: <20260417-tyr-ioctls-deps-v1-0-41c6e9bb061c@linux.dev> <20260417-tyr-ioctls-deps-v1-4-41c6e9bb061c@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: ABA6D80002 X-Rspamd-Server: rspam07 X-Stat-Signature: ue55btpkeqox1mbnz3wonwiioad53ibw X-Rspam-User: X-HE-Tag: 1776414525-571446 X-HE-Meta: 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 KblMIub+ +1yTvY7qizjlBDV/z2dJ9eZ4GwWN/17Q/p6oyAC2fugRXUVMKdHstRllKt/HTqG8uJUzGH3NqaF6zZ2JyMe/EGe8GH0BvzNJLK/x8DEBIJpWlr6H7T4ieyl3xULqxkzOFRE4r+irzJRIRE6IFuV0NLe0SjVt24qrBfp8+ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 17 Apr 2026 09:05:54 +0800=0D Alvin Sun wrote:=0D =0D > Add a helper to find the first present entry in the XArray.=0D > =0D > Returns the index of the first present entry, or None if the array=0D > is empty.=0D > =0D > Signed-off-by: Alvin Sun =0D > ---=0D > rust/kernel/xarray.rs | 22 ++++++++++++++++++++++=0D > 1 file changed, 22 insertions(+)=0D > =0D > diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs=0D > index 235fda0e394ba..e43129d032d9d 100644=0D > --- a/rust/kernel/xarray.rs=0D > +++ b/rust/kernel/xarray.rs=0D > @@ -217,6 +217,28 @@ pub fn remove(&mut self, index: usize) -> Option = {=0D > unsafe { T::try_from_foreign(ptr) }=0D > }=0D > =0D > + /// Finds the first present entry.=0D > + ///=0D > + /// Returns the index of the first present entry, or `None` if the a= rray is empty.=0D > + pub fn find(&mut self) -> Option {=0D > + let mut index =3D 0usize;=0D =0D Nit: I don't know if this verbosity can ever be useful, it can simply be `= =3D 0`;=0D =0D > + // SAFETY: `self.xa.xa` is always valid by the type invariant, a= nd we hold the lock.=0D > + let ptr =3D unsafe {=0D > + bindings::xa_find(=0D > + self.xa.xa.get(),=0D > + &mut index,=0D > + usize::MAX,=0D > + bindings::XA_PRESENT,=0D > + )=0D > + };=0D > +=0D > + if ptr.is_null() {=0D > + None=0D > + } else {=0D > + Some(index)=0D > + }=0D =0D This can be written with the `then_some` chain e.g., !ptr.is_null().then_so= me(..=0D .) but I don't know if it ever makes it more readable or simpler. I guess i= t's=0D up to preference.=0D =0D -Onur=0D =0D > + }=0D > +=0D > /// Stores an element at the given index.=0D > ///=0D > /// May drop the lock if needed to allocate memory, and then reacqui= re it afterwards.=0D > =0D > -- =0D > 2.43.0=0D > =0D