From nobody Fri Sep 10 19:40:23 2021 X-Original-To: hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 014EA17B0038; Fri, 10 Sep 2021 19:40:25 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4H5mS86fbFz3hyr; Fri, 10 Sep 2021 19:40:24 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from [192.168.0.88] (unknown [195.64.148.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: avg/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 54C9B535B; Fri, 10 Sep 2021 19:40:24 +0000 (UTC) (envelope-from avg@FreeBSD.org) Subject: Re: recvmsg() "short receive" after FIONREAD From: Andriy Gapon To: Mark Johnston Cc: "net@FreeBSD.org" , hackers@freebsd.org References: <500a2272-c1b3-3f97-0096-9fe8117c4b95@FreeBSD.org> <6f455869-cbdd-ee20-f2f8-f633e22071e9@FreeBSD.org> Message-ID: <4a2165c5-b97b-8fb7-9ada-0acae3197824@FreeBSD.org> Date: Fri, 10 Sep 2021 22:40:23 +0300 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.14.0 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-ThisMailContainsUnwantedMimeParts: N On 10/09/2021 22:38, Andriy Gapon wrote: > On 10/09/2021 22:35, Mark Johnston wrote: >> Indeed, I suspect that this is the problem.  Note that for >> kevent(EVFILT_READ) we subtract the number of control message bytes from >> the returned value, see filt_soread().  I wonder if FIONREAD should do >> the same thing. > > Thank you for the suggestion. > I think that it is a reasonable expectation that FIONREAD returns a number of > bytes that can be actually read. > I'll look at filt_soread(). kn_data = sbavail(&so->so_rcv) - so->so_rcv.sb_ctl; Is this it? Looks simple enough for a quick test :) -- Andriy Gapon