From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qv1-xf2f.google.com (mail-qv1-xf2f.google.com [IPv6:2607:f8b0:4864:20::f2f]) by sourceware.org (Postfix) with ESMTPS id 7FCF5385696A for ; Mon, 5 Sep 2022 19:51:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7FCF5385696A Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-qv1-xf2f.google.com with SMTP id o13so1177866qvw.12 for ; Mon, 05 Sep 2022 12:51:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date; bh=RPwIkw86uhlIH0U0KADV/NJ47HiXGyKgmMI2xQCweEQ=; b=PK07GY7uSMQTkP1qpkC6sm2GuriFXTdJCmT8N2AQE3HPN95FiM6NVm3U3naO6bTYOF tYmaMOdRQe39qhBUimki6sA93qCWNZDZ9V+KlWm7eAU3RwZJOShKnv+UF8kHRTzBiTit VbPnhVeF2JnQ6aLS4WIu263bDeMwBEavfzfIBxnIK0MYY6hbY+Cce8+Y3O4RcTyuGl6v lu86rUeibsGS9Q4CH91TOQgUt7wuq5A1Zxc455HUTomNnXCXpPxw9U5fsD28fwBEMKuF utBPpNZhuFIPDvtNRzkPszLqB+N+wx8hrU0jrPh/g0uR2pPTPQnBY91GjSr0govU+tkw RzGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date; bh=RPwIkw86uhlIH0U0KADV/NJ47HiXGyKgmMI2xQCweEQ=; b=0z2wASzJRRLhRVVTlrN05N2Qj7LcnMnlYAjbIGxTDkCOb1bGgk+ip0wst2uyjLtjsK qaEoYFhAU4hlF6J3fvHfkYl3pOybnz77jci6aWrBLvaxaOta1asi7YKplKXAmZ1VQdbm dr/qxUdh6EKXw6l4U3fCeg3JgjC9krHCcghI/2l9azok4dVevRvm61oAVFYHMyUmXEz0 LfJ6BYViy0mJvBEdA2Feqps3uc4nCi+MFIDV9G2XaGQ2bqF7wmxHdCjsq29TAcxpPU87 xwDlGifXnGw+lhyODLx3WqT/35Q+zrUTqs0ztH/Ud1SIYgYZQDoUvYzrZZkrzIGwtYyp P4Pw== X-Gm-Message-State: ACgBeo11VUR5O17LJ8jHx0wNfRGgYe0gSJrcVjMJ2/HM//8Jm5DAAkLD 32s6FYXis7g/YNqjlVeqWNEKxTP53sOmCetieP8= X-Google-Smtp-Source: AA6agR6yj/V2+YeLD2msS1Y/cXtP/AwBGIzrEEIFyi34PzAGytCvAZx6hUYNffDoYL8uvEfe7oCZCJuk6S2/V/u+cUk= X-Received: by 2002:a05:6214:62e:b0:499:2938:d49e with SMTP id a14-20020a056214062e00b004992938d49emr21200594qvx.84.1662407488800; Mon, 05 Sep 2022 12:51:28 -0700 (PDT) MIME-Version: 1.0 References: <20220905191411.1930373-1-adhemerval.zanella@linaro.org> In-Reply-To: <20220905191411.1930373-1-adhemerval.zanella@linaro.org> From: "H.J. Lu" Date: Mon, 5 Sep 2022 12:50:53 -0700 Message-ID: Subject: Re: [PATCH v2] elf: Use C11 atomics on _dl_mcount To: Adhemerval Zanella Cc: libc-alpha@sourceware.org, Wilco Dijkstra Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3023.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Mon, Sep 5, 2022 at 12:14 PM Adhemerval Zanella via Libc-alpha wrote: > > All atomic operation are counters, so relaxed MO should be suffice. > > Checked on x86_64-linux-gnu. > --- > elf/dl-profile.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/elf/dl-profile.c b/elf/dl-profile.c > index ec57e3a965..67a356bf66 100644 > --- a/elf/dl-profile.c > +++ b/elf/dl-profile.c > @@ -548,7 +548,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc) > size_t newfromidx; > to_index = (data[narcs].self_pc > / (HASHFRACTION * sizeof (*tos))); > - newfromidx = catomic_exchange_and_add (&fromidx, 1) + 1; > + newfromidx = atomic_fetch_add_relaxed (&fromidx, 1) + 1; > froms[newfromidx].here = &data[narcs]; > froms[newfromidx].link = tos[to_index]; > tos[to_index] = newfromidx; > @@ -558,14 +558,14 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc) > /* If we still have no entry stop searching and insert. */ > if (*topcindex == 0) > { > - unsigned int newarc = catomic_exchange_and_add (narcsp, 1); > + unsigned int newarc = atomic_fetch_add_relaxed (narcsp, 1) + 1; Shouldn't it be unsigned int newarc = atomic_fetch_add_relaxed (narcsp, 1); > > /* In rare cases it could happen that all entries in FROMS are > occupied. So we cannot count this anymore. */ > if (newarc >= fromlimit) > goto done; > > - *topcindex = catomic_exchange_and_add (&fromidx, 1) + 1; > + *topcindex = atomic_fetch_add_acquire (&fromidx, 1) + 1; > fromp = &froms[*topcindex]; > > fromp->here = &data[newarc]; > @@ -573,7 +573,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc) > data[newarc].self_pc = selfpc; > data[newarc].count = 0; > fromp->link = 0; > - catomic_increment (&narcs); > + atomic_fetch_add_relaxed (&narcs, 1); > > break; > } > @@ -586,7 +586,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc) > } > > /* Increment the counter. */ > - catomic_increment (&fromp->here->count); > + atomic_fetch_add_relaxed (&fromp->here->count, 1); > > done: > ; > -- > 2.34.1 > -- H.J.