Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D929C636CC for ; Sat, 4 Feb 2023 18:48:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231348AbjBDSsQ (ORCPT ); Sat, 4 Feb 2023 13:48:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233356AbjBDSsN (ORCPT ); Sat, 4 Feb 2023 13:48:13 -0500 Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E94E015543; Sat, 4 Feb 2023 10:48:11 -0800 (PST) Received: by mail-ej1-x62e.google.com with SMTP id mc11so23739243ejb.10; Sat, 04 Feb 2023 10:48:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:references:from:subject:cc:to:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=WTf3il7r+qUfnmE8kG0NPYBSRKTNHfVqKM3rJtokOrg=; b=j7YYbGOBZoGO07U6BsfJWa2yIbjdSF6bVuAmchsXj8289KvVyGiXoOOjqtqz1LqNwH pZPVe1RG7jI7ZaejnAQOYP3XL7oC8wW1O7Tz19JFXzdXj9F98sjY/dE00C/oMdwMTvgi okiJGPb4hyPxYNFf+iS4GeYmPKM1lp1QHDKWju5gdAtffoKORjx0NprU+D8ojuA73Cn6 8RPGjKl9F6j9aN/FtIelZXygioLLdfklwhuL7kixDu/66PtWJ6RINpyUo0+3fHLsyxRM 9v2upVU5YWCCxM93Fly1mwsdwudrYjf+goIYXjcN+7c3S5C7koRk8qRGFO3mzkiCkpF/ iXsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:references:from:subject:cc:to:message-id:date :content-transfer-encoding:mime-version:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=WTf3il7r+qUfnmE8kG0NPYBSRKTNHfVqKM3rJtokOrg=; b=X+DrOcoGy/o+Poau5BpbdIlmqkkl3S5Wsn0/BX3oJXx2YKg76NGqVK0sGwOykVoVTc M8TFxzywcmgq7exSLB388H/ALx4sXSGHnmwPGgt/UbWM+gxQoaVTE1H9ZENrhnVzifMU 33UIG7vMND0lU1pk8XRYp60aEl/BeJgn/VHD5rqKivMM4rfgq0JoLbfItRQf5Cxqe+mw p+tC4lmt+pcf1U9nAx8nfQY5nGP4uJwPyYCyu0OC9njZlDr9yHRRaafJUuVTZpXXDrfh +JIfWl3uZGdp3MGUFHEUR2eVtl3HR0FB/frJuqOMIstGSAtfpLFur37zOOPi/3BaJRi3 pVQA== X-Gm-Message-State: AO0yUKXujGt44boGBMYtEgUp14vDK3+mpoSmZ25tcbMh7HXTsf3DHDve VXtK7HScCItwObNeABiV1e0= X-Google-Smtp-Source: AK7set+w35CKWh4qe2pjguycwYZUgyWZznLOJ9omq/T90+qDammNPobTCd5Rj44E8fGAwXWwozGbPw== X-Received: by 2002:a17:906:7141:b0:877:7157:9358 with SMTP id z1-20020a170906714100b0087771579358mr5959833ejj.10.1675536490416; Sat, 04 Feb 2023 10:48:10 -0800 (PST) Received: from localhost (93-55-83-125.ip262.fastwebnet.it. [93.55.83.125]) by smtp.gmail.com with ESMTPSA id l2-20020a170906938200b007c11e5ac250sm3171286ejx.91.2023.02.04.10.48.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 04 Feb 2023 10:48:09 -0800 (PST) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 04 Feb 2023 19:48:08 +0100 Message-Id: To: "Boqun Feng" , , Cc: "Will Deacon" , "Peter Zijlstra" , "Mark Rutland" , "Miguel Ojeda" , "Alex Gaynor" , "Wedson Almeida Filho" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= Subject: Re: [RFC 2/5] rust: sync: Arc: Introduces ArcInner::count() From: "Vincenzo Palazzo" X-Mailer: aerc 0.14.0-38-gb2afc8117fb7 References: <20230201232244.212908-1-boqun.feng@gmail.com> <20230201232244.212908-3-boqun.feng@gmail.com> In-Reply-To: <20230201232244.212908-3-boqun.feng@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu Feb 2, 2023 at 12:22 AM CET, Boqun Feng wrote: > This allows reading the current count of a refcount in an `ArcInner`. > > Signed-off-by: Boqun Feng > --- Reviwed-by: Vincenzo Palazzo > 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); > =20 > +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, > } > =20 > +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 `se= lf`. > impl core::ops::Receiver for Arc {} > =20 > --=20 > 2.39.1