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[66.111.4.228]) by smtp.gmail.com with ESMTPSA id v3-20020ac87283000000b003b62e9c82ebsm12661001qto.48.2023.02.01.15.22.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Feb 2023 15:22:54 -0800 (PST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailauth.nyi.internal (Postfix) with ESMTP id 4043827C0054; Wed, 1 Feb 2023 18:22:54 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Wed, 01 Feb 2023 18:22:54 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrudefjedgudduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepuehoqhhu nhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrg htthgvrhhnpeegleejiedthedvheeggfejveefjeejkefgveffieeujefhueeigfegueeh geeggfenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe gsohhquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdei gedqudejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfih igmhgvrdhnrghmvg X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 1 Feb 2023 18:22:53 -0500 (EST) From: Boqun Feng To: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Will Deacon , Peter Zijlstra , Mark Rutland , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Vincenzo Palazzo Subject: [RFC 2/5] rust: sync: Arc: Introduces ArcInner::count() Date: Wed, 1 Feb 2023 15:22:41 -0800 Message-Id: <20230201232244.212908-3-boqun.feng@gmail.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230201232244.212908-1-boqun.feng@gmail.com> References: <20230201232244.212908-1-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This allows reading the current count of a refcount in an `ArcInner`. Signed-off-by: Boqun Feng --- rust/helpers.c | 6 ++++++ rust/kernel/sync/arc.rs | 9 +++++++++ 2 files changed, 15 insertions(+) diff --git a/rust/helpers.c b/rust/helpers.c index 09a4d93f9d62..afc5f1a39fef 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -46,6 +46,12 @@ bool rust_helper_refcount_dec_and_test(refcount_t *r) } EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); +unsigned int rust_helper_refcount_read(refcount_t *r) +{ + return refcount_read(r); +} +EXPORT_SYMBOL_GPL(rust_helper_refcount_read); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index fc680a4a795c..fbfceaa3096e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -127,6 +127,15 @@ struct ArcInner { data: T, } +impl ArcInner { + /// Returns the current reference count of [`ArcInner`]. + fn count(&self) -> u32 { + // SAFETY: `self.refcount.get()` is always a valid pointer, and `refcount_read()` is a + // normal atomic read (i.e. no data race) only requiring on the address is valid. + unsafe { bindings::refcount_read(self.refcount.get()) } + } +} + // This is to allow [`Arc`] (and variants) to be used as the type of `self`. impl core::ops::Receiver for Arc {} -- 2.39.1