From nobody Thu Sep 18 10:15:42 2025 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 7042DC47089 for ; Wed, 7 Dec 2022 16:44:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229749AbiLGQoB (ORCPT ); Wed, 7 Dec 2022 11:44:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229956AbiLGQn5 (ORCPT ); Wed, 7 Dec 2022 11:43:57 -0500 Received: from mail-lf1-x149.google.com (mail-lf1-x149.google.com [IPv6:2a00:1450:4864:20::149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4183D5E9CB for ; Wed, 7 Dec 2022 08:43:56 -0800 (PST) Received: by mail-lf1-x149.google.com with SMTP id q25-20020ac25a19000000b004b59452a20aso790597lfn.11 for ; Wed, 07 Dec 2022 08:43:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=R3UNgITk2mCHM+aO+s0l1dU1wLZipt6ouG5VCup5ogI=; b=Jz0dxAj0ez7bZFI3NVyATAAqCsijUj/bzAPgNXTFygZTZgQ7y23Uu5QmZcfivd00bR FmMEyREyeUPS7o3HvpZZNDrw54Yx1zKt/muSqK8Sr9e8cZTsd7f6bZQfVAaC02fU0qiA 0qw7J4effoSo8816N1fDYWHLcMSFieumfGy3ZND2thOacnib8n+YHGL1sjtx6EpfGfEr QTcIeXFfHOcBZHwtWestLk7LrC1y/fORCxalyHJDqBzrldLw6w/iMyiFCikm4kqhtT9I rOWvSSGCgPzneb18q9SmmAWALdrGRojrscCR+hddi8noVtF232wCoXfsvNc3KvOrCHDd b6og== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=R3UNgITk2mCHM+aO+s0l1dU1wLZipt6ouG5VCup5ogI=; b=m2AXej8Dwf27LuWsXwt7pfNyiWWpKP/K3VXnh7AZixerP5yXCgd4Q+Bh7MNIGW0uzp xO+TdUe3YIPzrsMSs2vMrbvllqXNHf+QWfBCYPwyuSrveW5rDEyhgHdTQklov0Oc1T8M 7xQMzI8edBw8k+BN54AV+eYqhcQic81BoIyRZ0SuO/oLnHeOLHfD6ntD9UECLNz3j1Gc 0cnHOse6sfRBsaQ54eIzQ/yQ6fEhT/sIMByKfsnYF9a3iBHS4qHtNjStelRBa2QHhtMJ lMPePZWoSOoscnpMm/JL47vRCfoofM751aqIzuQeYSVyVWzX7W80J/D2XPF29+F98zi0 6+2Q== X-Gm-Message-State: ANoB5pniY33BkuQmnfRc8tjDz4f9nFlXpMrqkBCjk9PNdIQn0O/8J+Yh ne4HOCXDI7HI527ZdeU1KgzwR9b+SXrF/sxf X-Google-Smtp-Source: AA0mqf6hwzNXlz8mWqisoOstIk8lU431OMAtI0FDtAlpn3oNcMNpSObbMyM4FovQgMHkq/Xk99Z3UP2pVjMWxsbu X-Received: from mclapinski.waw.corp.google.com ([2a00:79e0:9b:0:3d6d:f78e:bc73:df]) (user=mclapinski job=sendgmr) by 2002:a05:651c:12ca:b0:277:a9d:9355 with SMTP id 10-20020a05651c12ca00b002770a9d9355mr21109826lje.102.1670431434519; Wed, 07 Dec 2022 08:43:54 -0800 (PST) Date: Wed, 7 Dec 2022 17:43:37 +0100 In-Reply-To: <20221207164338.1535591-1-mclapinski@google.com> Mime-Version: 1.0 References: <20221207164338.1535591-1-mclapinski@google.com> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog Message-ID: <20221207164338.1535591-2-mclapinski@google.com> Subject: [PATCH 1/2] sched/membarrier: Introduce MEMBARRIER_CMD_GET_REGISTRATIONS From: Michal Clapinski To: Mathieu Desnoyers , "Paul E. McKenney" Cc: Ingo Molnar , Peter Zijlstra , Andrei Vagin , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Michal Clapinski Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Provide a method to query previously issued registrations. Signed-off-by: Michal Clapinski --- include/uapi/linux/membarrier.h | 4 ++++ kernel/sched/membarrier.c | 39 ++++++++++++++++++++++++++++++++- 2 files changed, 42 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/membarrier.h b/include/uapi/linux/membarrie= r.h index 737605897f36..5f3ad6d5be6f 100644 --- a/include/uapi/linux/membarrier.h +++ b/include/uapi/linux/membarrier.h @@ -137,6 +137,9 @@ * @MEMBARRIER_CMD_SHARED: * Alias to MEMBARRIER_CMD_GLOBAL. Provided for * header backward compatibility. + * @MEMBARRIER_CMD_GET_REGISTRATIONS: + * Returns a bitmask of previously issued + * registration commands. * * Command to be passed to the membarrier system call. The commands need to * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned= to @@ -153,6 +156,7 @@ enum membarrier_cmd { MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE =3D (1 << 6), MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ =3D (1 << 7), MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ =3D (1 << 8), + MEMBARRIER_CMD_GET_REGISTRATIONS =3D (1 << 9), =20 /* Alias for header backward compatibility. */ MEMBARRIER_CMD_SHARED =3D MEMBARRIER_CMD_GLOBAL, diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 0c5be7ebb1dc..2ad881d07752 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -159,7 +159,8 @@ | MEMBARRIER_CMD_PRIVATE_EXPEDITED \ | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED \ | MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \ - | MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK) + | MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK \ + | MEMBARRIER_CMD_GET_REGISTRATIONS) =20 static void ipi_mb(void *info) { @@ -540,6 +541,40 @@ static int membarrier_register_private_expedited(int f= lags) return 0; } =20 +static int membarrier_get_registrations(void) +{ + struct task_struct *p =3D current; + struct mm_struct *mm =3D p->mm; + int registrations_mask =3D 0, membarrier_state, i; + static const int states[] =3D { + MEMBARRIER_STATE_GLOBAL_EXPEDITED | + MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY, + MEMBARRIER_STATE_PRIVATE_EXPEDITED | + MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY, + MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE | + MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY, + MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ | + MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY + }; + static const int registration_cmds[] =3D { + MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED, + MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, + MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE, + MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ + }; + BUILD_BUG_ON(ARRAY_SIZE(states) !=3D ARRAY_SIZE(registration_cmds)); + + membarrier_state =3D atomic_read(&mm->membarrier_state); + for (i =3D 0; i < ARRAY_SIZE(states); ++i) { + if (membarrier_state & states[i]) { + registrations_mask |=3D registration_cmds[i]; + membarrier_state &=3D ~states[i]; + } + } + WARN_ON_ONCE(membarrier_state !=3D 0); + return registrations_mask; +} + /** * sys_membarrier - issue memory barriers on a set of threads * @cmd: Takes command values defined in enum membarrier_cmd. @@ -623,6 +658,8 @@ SYSCALL_DEFINE3(membarrier, int, cmd, unsigned int, fla= gs, int, cpu_id) return membarrier_private_expedited(MEMBARRIER_FLAG_RSEQ, cpu_id); case MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ: return membarrier_register_private_expedited(MEMBARRIER_FLAG_RSEQ); + case MEMBARRIER_CMD_GET_REGISTRATIONS: + return membarrier_get_registrations(); default: return -EINVAL; } --=20 2.39.0.rc0.267.gcb52ba06e7-goog