From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f41.google.com (mail-ed1-f41.google.com [209.85.208.41]) (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 512618627D for ; Mon, 29 Apr 2024 17:34:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714412072; cv=none; b=ARFdupo7PP+CjOPlKZzJnr49ZnKUR6k9+JVADSxHOlmjfnpw/qcGq4gsgfsYo8x7bqJKnuCK3lS7cW8LH6tL1EUACq6kF/6C5vhcOvKQf47wd9uPsls8EVdfC9undcXbtY4FrqoRlS9q5beTKzp+ZXRjDd4uL0PHzniBX/qJLLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714412072; c=relaxed/simple; bh=EkPSKv49pNPDE1MKv1JG6ShiA98XxcQawgYaYEZAfgU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=V5P2Gq/qPnHJPUWW94X5sZ/HGZwR64HOmheZHnbcneUhUA6eyBUld26kZHbafy/Rz+TPZYsiIgqjNfVTpV5ClBDSMUKQrpjHUTH67+W62SO35szwQ33IdpyAX3BKtZA4nvE7e+JOHsxK9JWxbN7xh2HbkeDpe82XoDcFH1VA1sE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.208.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ed1-f41.google.com with SMTP id 4fb4d7f45d1cf-56e48d0a632so7424376a12.2 for ; Mon, 29 Apr 2024 10:34:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714412068; x=1715016868; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=J6Mnhr84frKfp8Q+ozh89M+AylhkV35gyu23vGYZQ+g=; b=T3Xz4PbsfQkwf9eFWkyabkT05sodZY9zjciXqS3XN/0LPOdgUMeJcyogGuNTOxFuhB 4DjgA7W4I1EpAUk5HSAHPw/RN3YB1q13aSH7Em09Prs8zGhTg4+mtK1aDAmW6qr9EW+X v6DHxsPIKZd5u8TTJeF4gKhQAj6UlqItEtHVKnutbztuXxRYS9wLFmXGUsw9r6cpVySb buP+fabk9yDaoXJLg03Kqddka/lbC5XlAezCL2CNbjpGLcwNKAA/LRYELK2daYdvOiKk fx4R9Ujj9qM7v+CRdUi9POVxrRb53fCI5nlm/K4w5tUFGIjNcWnHH5DYhvi7Fw2hZ13V EmpQ== X-Gm-Message-State: AOJu0Yxqzf6Ah7U8eRL9t1n/sAgB/rlkQFwzfqa6UDxfPsoVITRR0/0t nX3qVC2wBLUAuN8US2pgvIqwAXW5wkVx3kPTPyf8xb05Vl941GqbWfo5SQ== X-Google-Smtp-Source: AGHT+IGoCqEbOyr0cmPSwdggv7OjSvZCv8a+72JUjJucmZst77qo55d04CLuI7VnClEPV6UXIuLBfw== X-Received: by 2002:a50:c34d:0:b0:572:4e6b:958 with SMTP id q13-20020a50c34d000000b005724e6b0958mr9679963edb.2.1714412068362; Mon, 29 Apr 2024 10:34:28 -0700 (PDT) Received: from gmail.com (fwdproxy-lla-001.fbsv.net. [2a03:2880:30ff:1::face:b00c]) by smtp.gmail.com with ESMTPSA id cs14-20020a0564020c4e00b005723e8610d2sm5095817edb.77.2024.04.29.10.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Apr 2024 10:34:27 -0700 (PDT) Date: Mon, 29 Apr 2024 10:34:26 -0700 From: Breno Leitao To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org Subject: Re: KCSAN in fuse (fuse_request_end <-> fuse_request_end) Message-ID: References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Apr 29, 2024 at 04:18:56PM +0200, Miklos Szeredi wrote: > On Fri, 26 Apr 2024 at 18:18, Breno Leitao wrote: > > > fuse_request_end() reads and writes to ->num_background while holding > > the bg_lock, but fuse_readahead() does not hold any lock before reading > > ->num_background. That is what KCSAN seems to be complaining about. > > > > Should we get ->bg_lock before reading ->num_background? > > Probably not necessary. Does wrapping that access in READ_ONCE() fix > the complaint? Yes, reading ->num_background using READ_ONCE() in the fuse_readahead() path fix KCSAN complaint. Should I sent it for review? Thanks