linux-kernel - [tip: locking/core] rust: sync: lock: Add an example for Guard:: Lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <174139248296.14745.13317521669976622612.tip-bot2@tip-bot2>
Date: Sat, 08 Mar 2025 00:08:02 -0000
From: "tip-bot2 for Boqun Feng" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Boqun Feng <boqun.feng@...il.com>, Ingo Molnar <mingo@...nel.org>,
 Benno Lossin <benno.lossin@...ton.me>, Alice Ryhl <aliceryhl@...gle.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: locking/core] rust: sync: lock: Add an example for Guard:: Lock_ref()

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     c2849afafd08a1c3ad881129de48ebe1642f7675
Gitweb:        https://git.kernel.org/tip/c2849afafd08a1c3ad881129de48ebe1642f7675
Author:        Boqun Feng <boqun.feng@...il.com>
AuthorDate:    Fri, 07 Mar 2025 15:26:58 -08:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sat, 08 Mar 2025 00:55:04 +01:00

rust: sync: lock: Add an example for Guard:: Lock_ref()

To provide examples on usage of `Guard::lock_ref()` along with the unit
test, an "assert a lock is held by a guard" example is added.

(Also apply feedback from Benno.)

Signed-off-by: Boqun Feng <boqun.feng@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Benno Lossin <benno.lossin@...ton.me>
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
Link: https://lore.kernel.org/r/20250223072114.3715-1-boqun.feng@gmail.com
Link: https://lore.kernel.org/r/20250307232717.1759087-9-boqun.feng@gmail.com
---
 rust/kernel/sync/lock.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 8e7e6d5..f53e87d 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -201,6 +201,30 @@ unsafe impl<T: Sync + ?Sized, B: Backend> Sync for Guard<'_, T, B> {}
 
 impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
     /// Returns the lock that this guard originates from.
+    ///
+    /// # Examples
+    ///
+    /// The following example shows how to use [`Guard::lock_ref()`] to assert the corresponding
+    /// lock is held.
+    ///
+    /// ```
+    /// # use kernel::{new_spinlock, stack_pin_init, sync::lock::{Backend, Guard, Lock}};
+    ///
+    /// fn assert_held<T, B: Backend>(guard: &Guard<'_, T, B>, lock: &Lock<T, B>) {
+    ///     // Address-equal means the same lock.
+    ///     assert!(core::ptr::eq(guard.lock_ref(), lock));
+    /// }
+    ///
+    /// // Creates a new lock on the stack.
+    /// stack_pin_init!{
+    ///     let l = new_spinlock!(42)
+    /// }
+    ///
+    /// let g = l.lock();
+    ///
+    /// // `g` originates from `l`.
+    /// assert_held(&g, &l);
+    /// ```
     pub fn lock_ref(&self) -> &'a Lock<T, B> {
         self.lock
     }