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[103.168.172.200]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c6a72985a8sm693681085a.54.2026.01.18.17.03.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 18 Jan 2026 17:03:55 -0800 (PST) Received: from phl-compute-04.internal (phl-compute-04.internal [10.202.2.44]) by mailfauth.phl.internal (Postfix) with ESMTP id D45BCF40071; Sun, 18 Jan 2026 20:03:54 -0500 (EST) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-04.internal (MEProxy); Sun, 18 Jan 2026 20:03:54 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddufeeivddtucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrghtth gvrhhnpeehudfgudffffetuedtvdehueevledvhfelleeivedtgeeuhfegueevieduffei vdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegsoh hquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdeigedq udejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfihigmh gvrdhnrghmvgdpnhgspghrtghpthhtohepvdejpdhmohguvgepshhmthhpohhuthdprhgt phhtthhopeguihhrkhdrsggvhhhmvgesghhmrghilhdrtghomhdprhgtphhtthhopehruh hsthdqfhhorhdqlhhinhhugiesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthho pehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtth hopehrtghusehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepohhjvggurges khgvrhhnvghlrdhorhhgpdhrtghpthhtohepghgrrhihsehgrghrhihguhhordhnvghtpd hrtghpthhtohepsghjohhrnhefpghghhesphhrohhtohhnmhgrihhlrdgtohhmpdhrtghp thhtoheplhhoshhsihhnsehkvghrnhgvlhdrohhrghdprhgtphhtthhopegrrdhhihhnug gsohhrgheskhgvrhhnvghlrdhorhhg X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 18 Jan 2026 20:03:54 -0500 (EST) Date: Mon, 19 Jan 2026 09:03:52 +0800 From: Boqun Feng To: Dirk Behme Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, Miguel Ojeda , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Will Deacon , Peter Zijlstra , Mark Rutland , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , FUJITA Tomonori Subject: Re: [PATCH 5/5] rust: sync: rcu: Add RCU protected pointer Message-ID: References: <20260117122243.24404-1-boqun.feng@gmail.com> <20260117122243.24404-6-boqun.feng@gmail.com> <56d1cc0e-df60-4e2b-bfa9-b29ec48a76b6@gmail.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56d1cc0e-df60-4e2b-bfa9-b29ec48a76b6@gmail.com> On Sun, Jan 18, 2026 at 09:28:35AM +0100, Dirk Behme wrote: [...] > > + /// ``` > > + pub fn dereference<'rcu>(&self, _rcu_guard: &'rcu Guard) -> Option> { > > + // Ordering: Address dependency pairs with the `store(Release)` in copy_update(). > > + let ptr = self.as_atomic().load(Relaxed); > > + > > + if !ptr.is_null() { > > + // SAFETY: > > > Would it be an option to take an early return here and with this drop > one indentation level of the larger `SAFETY` comment? > > if ptr.is_null() { > return None; > } > > // SAFETY: > ... > Some(unsafe { P::borrow(ptr) }) > > Same for `Drop for Rcu

` below. > > Make sense. > > + // - Since `ptr` is not null, so it has to be a return value of `P::into_foreign()`. > > + // - The returned `Borrowed<'rcu>` cannot outlive the RCU Guar, this guarantees the > > Guar -> Guard > Fixed! Thank you! Regards, Boqun