From mboxrd@z Thu Jan 1 00:00:00 1970 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 AB867C4332F for ; Mon, 25 Apr 2022 14:21:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232966AbiDYOY2 (ORCPT ); Mon, 25 Apr 2022 10:24:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242230AbiDYOY1 (ORCPT ); Mon, 25 Apr 2022 10:24:27 -0400 Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EB8A1C90F for ; Mon, 25 Apr 2022 07:21:23 -0700 (PDT) Received: by mail-il1-x136.google.com with SMTP id k12so9434247ilv.3 for ; Mon, 25 Apr 2022 07:21:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gBB3rIq31HTt0a91neDmCOiC54dYmIJQc4bKJW/WfqE=; b=XmJI12QPKE6ZSXjfgANLr4kMmvGtAlPQj809GWawJ2Xy0N5AlOgS4ROPy6BKBBjs60 pEDsMqyydkzNqTz/S8VpdT2/uhuQsaW6g8G854WivrEdY1QUlWQQ2amaOVJ0bJIkQsZo Rudz6wDW100se6cR8MGnL4JBHweH7JXWP+/s2mFF4YfS0ikwAXvE7lebO2VNbI1z5Xmu W1/dz8AUXtLvei4bo6BOg9/k940gRgwnqgb8XRg4LXPsPyCGeoligYzlzvo7+YIWzGT4 Bf9kK/DlWMYdkQO6xJBOhnSsLJMpHVYor9fEpqno00AS/NywSU67cqW9ViVCySafDGSv /ipw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gBB3rIq31HTt0a91neDmCOiC54dYmIJQc4bKJW/WfqE=; b=6b9wGHA/f2NOgUBnCXduwqAAtMfRw2t+GsHtMqhtLoyYDlgwloJCic6Sl5r70Fpn64 LuJhOLTY+nnhmC7qULM0NY4qAPV6GMOZYH2Sq6rC9iH4EBZ9OWE/xCXxzAMrlhGUFD/I evMmH0xFTbEm3WXsi3lgNZpg6C7zQe6vb+pzexXzxLS+MghC3z1fCDtROnj9C8xPfyZf u1jFAd9YFNMLqB99aaqsM53HpyOfdnU49iVNARlGsKuzP/zG4KO335MFwQgb3WZ0yFjP pp+ebsI3C7FbzaTwWfFX04oXrVMgoCBKPm+9z4Gb5iyF6wpwEJXzd+s5oJ9P2MXCyIU1 dV1Q== X-Gm-Message-State: AOAM5310ywW81KNCPJZQnZ2u3qLZ0elbZbcCkor5QqJCeuONNdcNUKHn e6nPdlytfDvarwulaBg7659QaLS54sPpOg== X-Google-Smtp-Source: ABdhPJxLvhbXPDdwmwkJtbnbxsQYnXntURqP0S0EXFftRJ6qAhO0ktw0ok0wf9tpnpa9fMMiw1lAhg== X-Received: by 2002:a92:c564:0:b0:2cc:4661:3c60 with SMTP id b4-20020a92c564000000b002cc46613c60mr7052108ilj.49.1650896482527; Mon, 25 Apr 2022 07:21:22 -0700 (PDT) Received: from m1.localdomain ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id p6-20020a0566022b0600b0064c59797e67sm8136737iov.46.2022.04.25.07.21.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Apr 2022 07:21:21 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 2/6] io_uring: serialize ctx->rings->sq_flags with atomic_or/and Date: Mon, 25 Apr 2022 08:21:14 -0600 Message-Id: <20220425142118.1448840-3-axboe@kernel.dk> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220425142118.1448840-1-axboe@kernel.dk> References: <20220425142118.1448840-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Rather than require ctx->completion_lock for ensuring that we don't clobber the flags, use the atomic bitop helpers instead. This removes the need to grab the completion_lock, in preparation for needing to set or clear sq_flags when we don't know the status of this lock. Signed-off-by: Jens Axboe --- fs/io_uring.c | 36 ++++++++++-------------------------- 1 file changed, 10 insertions(+), 26 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index bf95ef9240e5..511b52e4b9fd 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -170,7 +170,7 @@ struct io_rings { * The application needs a full memory barrier before checking * for IORING_SQ_NEED_WAKEUP after updating the sq tail. */ - u32 sq_flags; + atomic_t sq_flags; /* * Runtime CQ flags * @@ -2060,8 +2060,7 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force) all_flushed = list_empty(&ctx->cq_overflow_list); if (all_flushed) { clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq); - WRITE_ONCE(ctx->rings->sq_flags, - ctx->rings->sq_flags & ~IORING_SQ_CQ_OVERFLOW); + atomic_andnot(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags); } io_commit_cqring(ctx); @@ -2155,8 +2154,7 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data, } if (list_empty(&ctx->cq_overflow_list)) { set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq); - WRITE_ONCE(ctx->rings->sq_flags, - ctx->rings->sq_flags | IORING_SQ_CQ_OVERFLOW); + atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags); } ocqe->cqe.user_data = user_data; @@ -8477,23 +8475,6 @@ static inline bool io_sqd_events_pending(struct io_sq_data *sqd) return READ_ONCE(sqd->state); } -static inline void io_ring_set_wakeup_flag(struct io_ring_ctx *ctx) -{ - /* Tell userspace we may need a wakeup call */ - spin_lock(&ctx->completion_lock); - WRITE_ONCE(ctx->rings->sq_flags, - ctx->rings->sq_flags | IORING_SQ_NEED_WAKEUP); - spin_unlock(&ctx->completion_lock); -} - -static inline void io_ring_clear_wakeup_flag(struct io_ring_ctx *ctx) -{ - spin_lock(&ctx->completion_lock); - WRITE_ONCE(ctx->rings->sq_flags, - ctx->rings->sq_flags & ~IORING_SQ_NEED_WAKEUP); - spin_unlock(&ctx->completion_lock); -} - static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries) { unsigned int to_submit; @@ -8609,8 +8590,8 @@ static int io_sq_thread(void *data) bool needs_sched = true; list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) { - io_ring_set_wakeup_flag(ctx); - + atomic_or(IORING_SQ_NEED_WAKEUP, + &ctx->rings->sq_flags); if ((ctx->flags & IORING_SETUP_IOPOLL) && !wq_list_empty(&ctx->iopoll_list)) { needs_sched = false; @@ -8635,7 +8616,8 @@ static int io_sq_thread(void *data) mutex_lock(&sqd->lock); } list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) - io_ring_clear_wakeup_flag(ctx); + atomic_andnot(IORING_SQ_NEED_WAKEUP, + &ctx->rings->sq_flags); } finish_wait(&sqd->wait, &wait); @@ -8645,7 +8627,7 @@ static int io_sq_thread(void *data) io_uring_cancel_generic(true, sqd); sqd->thread = NULL; list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) - io_ring_set_wakeup_flag(ctx); + atomic_or(IORING_SQ_NEED_WAKEUP, &ctx->rings->sq_flags); io_run_task_work(); mutex_unlock(&sqd->lock); @@ -12399,6 +12381,8 @@ static int __init io_uring_init(void) BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST); BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int)); + BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32)); + req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); return 0; -- 2.35.1