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 5D78CC25B08 for ; Wed, 17 Aug 2022 16:44:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240611AbiHQQo1 (ORCPT ); Wed, 17 Aug 2022 12:44:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240600AbiHQQoY (ORCPT ); Wed, 17 Aug 2022 12:44:24 -0400 Received: from mail-io1-xd31.google.com (mail-io1-xd31.google.com [IPv6:2607:f8b0:4864:20::d31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55A0D5140A for ; Wed, 17 Aug 2022 09:44:22 -0700 (PDT) Received: by mail-io1-xd31.google.com with SMTP id i77so7514197ioa.7 for ; Wed, 17 Aug 2022 09:44:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=BBPOTlvzySXjn/em5t4brvWTEibIOSecbBA05J6WvbU=; b=DlfEC0Y9wGKBCJWX/pdytAVPeMNxNsIPEwycvjVjk0QbNAF2Z9bpkhz6ekAeQCf3h7 eb/oRpgk1uF6r788ujdM5ZBqTxGooSxwDdFH2QVGxsRmbwjUtR66BN3sNuY862m1io+/ ZA6eIVgNtxuW6Fm7Gy157WgyJqdepS2fTTC1FBx47Y6p/L81Ho5pRb6emXHeJ/1d6fiy QuwPuD5UIBOK2WkNY4Igfa4DABfq+HKDihCIqd80j+OM0HgueitDOwJZ3sIpEqalpWlZ 643bRwapGjWaqPgpKOeFToZawM8dUwrYHUzRVY944e9hbenHcpFs/fAdCPgoaAqV1VRq B2ng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=BBPOTlvzySXjn/em5t4brvWTEibIOSecbBA05J6WvbU=; b=W1MJMYny0PglqsxSFDCQvUBP1piabzJQQbLnOy/jUAL89Wl7IbP2xEyB53Bmu4aFCh qpW5wo5wqIE5mSZ7+vIIHFzFiWC6NyV0JcE+Vq34B6Mz8jBJDR46bue3cU1nH4eVYi4e UYDg2Xx8dW8TqVq5RFrJz0moenYO8Q11t5IVMHVhPhXvcc/1+7maj2bkwIBmTXDh4PK4 /+8/z3FhQ5WeprPw+soiwygMnEGNkdESBc+ynaZxHVLdi0+pd3MJOQbhDpkSURxQXiDF ufWvhNvtUCGDU6VpTsBuahozziy2m0sLq4+vdzcKQxfLhLbRrZG/v3hyduey/htma7fn JUTw== X-Gm-Message-State: ACgBeo2fYrapcfL0xs7/PoTXaXtEoqHYnw7LSpVXKda/Ivt03EevTvlc x3FtTsP1gB7d6BcK4TDom4r14A== X-Google-Smtp-Source: AA6agR4LlYiDbThwD0mvJgsbHNQNo+BN3kuuZ2sl+8WTJzfDgRPUo1PBWKDZY58MSPCbCuwDMPJBbA== X-Received: by 2002:a6b:3ec2:0:b0:67c:6baf:a51f with SMTP id l185-20020a6b3ec2000000b0067c6bafa51fmr11690579ioa.160.1660754661680; Wed, 17 Aug 2022 09:44:21 -0700 (PDT) Received: from [192.168.1.170] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id l10-20020a02cd8a000000b0033ebbb649fasm5718109jap.101.2022.08.17.09.44.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 17 Aug 2022 09:44:20 -0700 (PDT) Message-ID: <6d6df27f-a5c3-d6dd-ac1c-1d1c0fe53aaa@kernel.dk> Date: Wed, 17 Aug 2022 10:44:16 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] eventfd: guard wake_up in eventfd fs calls as well Content-Language: en-US To: Dylan Yudaken , viro@zeniv.linux.org.uk, bcrl@kvack.org Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-kernel@vger.kernel.org, Kernel-team@fb.com References: <20220816135959.1490641-1-dylany@fb.com> From: Jens Axboe In-Reply-To: <20220816135959.1490641-1-dylany@fb.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 8/16/22 07:59, Dylan Yudaken wrote: > Guard wakeups that the user can trigger, and that may end up triggering a > call back into eventfd_signal. This is in addition to the current approach > that only guards in eventfd_signal. > > Rename in_eventfd_signal -> in_eventfd at the same time to reflect this. > > Without this there would be a deadlock in the following code using libaio: > > int main() > { > struct io_context *ctx = NULL; > struct iocb iocb; > struct iocb *iocbs[] = { &iocb }; > int evfd; > uint64_t val = 1; > > evfd = eventfd(0, EFD_CLOEXEC); > assert(!io_setup(2, &ctx)); > io_prep_poll(&iocb, evfd, POLLIN); > io_set_eventfd(&iocb, evfd); > assert(1 == io_submit(ctx, 1, iocbs)); > write(evfd, &val, 8); > } Reviewed-by: Jens Axboe -- Jens Axboe