From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f176.google.com (mail-pf1-f176.google.com [209.85.210.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D7A282F6175 for ; Wed, 27 Aug 2025 22:23:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756333413; cv=none; b=VpCZMFwmlTLqYgK8ns3YXT7YSzGMnc0ooQ5ClNc0sCdUhrbMepUm1CpfBTEFgH7Z+X8Ty7dDGVG+JjSEBJ+n0FSi2K8sQYi0Z5qpSotaex6xxwDQw01aprQA7AJxru3L+xVB4aq4SG/9FNdY5xv2DG96A5yrF5FpQt/6CZrkFSU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756333413; c=relaxed/simple; bh=Koedtw7q0lWiWCcYzjgUSinsr/wTxwCoNrsLzxhoFtQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XoHSGBTrlT6GPzpE1HM8lvsbjXrnEuoi2Cl49VwdtwZp4RjRXOS2yu6Nk1gJAya2P1GX/bCtExjApKQf3zs2UIaMpNnOOTIRRavdfJ90S5gXiZ2EFl1fq2y8ZBTPKdMp9BXcxB0R9Pn+7tXLjbFf2AONS2o0dujhSFF47h2pvJ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=BWwsJX2H; arc=none smtp.client-ip=209.85.210.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="BWwsJX2H" Received: by mail-pf1-f176.google.com with SMTP id d2e1a72fcca58-771e987b4e6so297709b3a.2 for ; Wed, 27 Aug 2025 15:23:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1756333410; x=1756938210; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=pxFYz5su5aGOBTMJArO0RJNHBnuvaDOgygQdn3ZQKyw=; b=BWwsJX2H9DITW32BrGbArrMOkBoMCV0xsriyFVr2hyE6XAylX2VJ4w7wuMWtZSMA1M XKQKOnjjPFyfwvoonK2xO0wFVEJAkVQDLBJUJHs2ETQp1Uf8j9+bci+3+B8Kxm5ehFJA VowsXvQxrDB0su5OsQkleRY36IH1hruM2s4NeC44vcZsLv7TKC4xJIRrsou499k9jSgj 7TbstJX21/LPYuOggew3iI+H+qBTx14lVf6J6a48zLrZgpfaIM7DQez2qzRQZMbMxaz9 AI+P1LtcTzmL96GsMDfikwjaG1OsIMEQMDxwd6LOk8qih0clxLBiw81DHbX42bkSuv3O V7+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756333410; x=1756938210; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pxFYz5su5aGOBTMJArO0RJNHBnuvaDOgygQdn3ZQKyw=; b=grAFypb7yTwfERew4qXRkF+ActrtAz7ZFHVQT0n+md/kwQbwIfYh8FZVwi68e40fL9 3i3KEsKal43OTJoA7O6MBvwznmfy7TdSc2PnvYaOiB6IMQHke/998e8U7pd5rdEaNlFv DAS5shALj86E2GNahMc4DwYsMmtSosm4KCOu8XI+doAYqIzT1BVI2ap1ASIzrWyMbOju q9qjZSSUSPiloQlkjFp4GJxaf57PQMRInbgPopARCOu5dmeL9gVX8p3kounAdDrxGJQa l7vN7UU1OH+Vgj/aVZmCuycvSW39psUP7eBIPur+QvoJt713gsINHfuFj6r2HiRNG78D rADw== X-Forwarded-Encrypted: i=1; AJvYcCUd9nRUcxHndsWhdyXfM2MSJfZzqrE0mLaI8OIFXFpZIx6ZKZ6zWmT/AUzll60OHBPwAwO+xOlutOYiblk=@vger.kernel.org X-Gm-Message-State: AOJu0YzaLlWGwaUVQR2SnFpqfR581SBSHRTN48jVDvmqxEjk5VbRfj5b dVz5x0nt/kYWyDgWUJAJYH1aVlczeUP0c8NVxABH0jyLS+C+q25E5M8QiOAwn0fKAXzIL+i4CpX 2Nfa+ X-Gm-Gg: ASbGncv1mHjM6uweaJ3k6gnHw6dtdKysJZSZRpQKswpubzFlFTATebBc6CQB9CVMVa9 IH28HJ3wM1TXPaD37791pygdctf7uKL/kmWNp0B2xJy39VfPHg4qUBq8Ljxd/vzr/4C6LQCdqrD QWxGx/5ZwYUJ+953sDoIXSpU6+VWDSGKPC8LnkKe7wbNnsv4lShqH6+mPZLFumPvgNiSGwPWz/B 4wZN1VTsfcIZpFgglO4TG4AtWoZilDVeq8rnjO0QTJJXSkeNNWFf6MkIwvZIGY2fhhBaDMviXzZ koTOvJQ46Mq4N9pRftcdskHsI9DizVeBPl2TM115bWuAydmxliTweKCYhsQD66KjCoK9IVvCXEG 8viM7GWyfTON5EpuvRcUD X-Google-Smtp-Source: AGHT+IH3o5DBqG938ns4gTHALqTiqdJfZVA/v8WB+nBjR0/wmCjbESOn8ppRetrlrQ4Ln7XLDlrgzw== X-Received: by 2002:a17:902:f60d:b0:248:79d4:939a with SMTP id d9443c01a7336-24879d4964emr82700735ad.29.1756333410184; Wed, 27 Aug 2025 15:23:30 -0700 (PDT) Received: from [192.168.1.150] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-248b7299dd1sm15506835ad.131.2025.08.27.15.23.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Aug 2025 15:23:29 -0700 (PDT) Message-ID: <7ac936ab-ff4f-457c-a745-56bccaa19a08@kernel.dk> Date: Wed, 27 Aug 2025 16:23:28 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] io_uring/kbuf: fix infinite loop in io_kbuf_inc_commit() To: Keith Busch Cc: Qingyue Zhang , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Suoxing Zhang References: <20250827114339.367080-1-chunzhennn@qq.com> <4b8eb795-239f-4f46-af4f-7a05056ab516@kernel.dk> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/27/25 3:59 PM, Keith Busch wrote: > On Wed, Aug 27, 2025 at 03:45:28PM -0600, Jens Axboe wrote: >>> + buf_len = READ_ONCE(buf->len); >>> + this_len = min_t(int, len, buf_len); >>> + buf_len -= this_len; >>> + if (buf_len) { >>> buf->addr += this_len; >>> + buf->len = buf_len; >>> return false; >>> } >>> + buf->len = 0; > > Purely for symmetry, assigning buf->len ought to be a WRITE_ONCE. I did think about that, perhaps I should've mentioned it in the commit message. While the reader side is important for the reasons stated, the updating of buf->len isn't really as only the serialized kernel side will do it. Hence the WRITE_ONCE() should not be needed on the write side, outside of perhaps documenting that this is a shared buffer. -- Jens Axboe