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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6AC5C433ED for ; Sun, 11 Apr 2021 00:51:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0D6D610E5 for ; Sun, 11 Apr 2021 00:51:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234970AbhDKAvY (ORCPT ); Sat, 10 Apr 2021 20:51:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234944AbhDKAvX (ORCPT ); Sat, 10 Apr 2021 20:51:23 -0400 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 895C4C06138B for ; Sat, 10 Apr 2021 17:51:08 -0700 (PDT) Received: by mail-wm1-x32b.google.com with SMTP id g18-20020a7bc4d20000b0290116042cfdd8so6671212wmk.4 for ; Sat, 10 Apr 2021 17:51:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=5/kHDtCTWA+k8pfcg6n0eofFa3PpD0Dl5r17Kpx5+qQ=; b=XSNevgys+WjA1nSJGe2qmZXfeEQFKlzKWyly8vfNtzuPCke2HB2BTCfcn90xNTFcQb Rhw7eXogO4S4FHg8Dqk87MbE3/RZRDTTnfkQSk5GRiU6g6RZK976v9zZkAPw2g7eVGfr /vnPhVeM4SIgL+HpAZdtgjAxqtAxRujFnAQe4rl7OiecfJ3WbYxvgIteOQFgQgdMrlpa T81lbjpKdbBYBnIrqgH4P32H9g9GZGP+Qnp/7cAwYwfEnm72xd1yvM50mWMUNHWG5kYT jarm4AKMkN5VhmzQ+l5+K7QYt4yBv2qcT/MVM14p9nB4/4adqLOLxP0VZXEgYhZiT/o2 30NQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5/kHDtCTWA+k8pfcg6n0eofFa3PpD0Dl5r17Kpx5+qQ=; b=IJVow9+D4dPB0biKYYlMvKR23qNtkbD9giEXtA79D75q4KM+K4HkGkFZzKaPEA+BAr D6x62Jeh4Dw/z3daLYJmY5a6tFp435MAMwbZtlQwJRbXl/ui/pIW86xW3lUMCXzLeQck cy1r5wxLmVRq4gJzsD8StZZfgq7lqwDZ3dqHN+A+7TkFzMtRoSyqqor38WPahJwTQPJJ qz9lztZIuSgdnDy81PQ02afo7OkwcVQn+gBfZXW8j/lA3P6B9zmViJUeuBuFBSlqgcgh tqO9xU9bqK5KCd46rxNPOa8rMMAGSxsJk/HiMTmMwbfQ0/g6WV8JKM9a48Jjig7wmwKP wiPQ== X-Gm-Message-State: AOAM5312aO30WubosmAbq5sdyuK0W/nVfj1xexedaOT4WMJ2hyHEHXOm b0Pbqy8muA0hZHNQPd+0uIs= X-Google-Smtp-Source: ABdhPJw36txWEpOvqK4RCYblfQ4da1JMGiKQby7lFYUNTEF1k9wjZvbQz8U40RtWHZBx+MUGLisyiA== X-Received: by 2002:a1c:7519:: with SMTP id o25mr19713237wmc.35.1618102267409; Sat, 10 Apr 2021 17:51:07 -0700 (PDT) Received: from localhost.localdomain ([85.255.237.117]) by smtp.gmail.com with ESMTPSA id y20sm9204735wma.45.2021.04.10.17.51.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Apr 2021 17:51:07 -0700 (PDT) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Subject: [PATCH 16/16] io_uring: return back safer resurrect Date: Sun, 11 Apr 2021 01:46:40 +0100 Message-Id: <7a080c20f686d026efade810b116b72f88abaff9.1618101759.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Revert of revert of "io_uring: wait potential ->release() on resurrect", which adds a helper for resurrect not racing completion reinit, as was removed because of a strange bug with no clear root or link to the patch. Was improved, instead of rcu_synchronize(), just wait_for_completion() because we're at 0 refs and it will happen very shortly. Specifically use non-interruptible version to ignore all pending signals that may have ended prior interruptible wait. This reverts commit cb5e1b81304e089ee3ca948db4d29f71902eb575. Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 2a465b6e90a4..257eddd4cd82 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1083,6 +1083,18 @@ static inline void io_req_set_rsrc_node(struct io_kiocb *req) } } +static void io_refs_resurrect(struct percpu_ref *ref, struct completion *compl) +{ + bool got = percpu_ref_tryget(ref); + + /* already at zero, wait for ->release() */ + if (!got) + wait_for_completion(compl); + percpu_ref_resurrect(ref); + if (got) + percpu_ref_put(ref); +} + static bool io_match_task(struct io_kiocb *head, struct task_struct *task, struct files_struct *files) @@ -9798,12 +9810,11 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, if (ret < 0) break; } while (1); - mutex_lock(&ctx->uring_lock); if (ret) { - percpu_ref_resurrect(&ctx->refs); - goto out_quiesce; + io_refs_resurrect(&ctx->refs, &ctx->ref_comp); + return ret; } } @@ -9896,7 +9907,6 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, if (io_register_op_must_quiesce(opcode)) { /* bring the ctx back to life */ percpu_ref_reinit(&ctx->refs); -out_quiesce: reinit_completion(&ctx->ref_comp); } return ret; -- 2.24.0