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([2a01:e0a:e10:ef90:8e19:3414:44f0:befd]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-422f641abcfsm20115995e9.47.2024.06.13.03.58.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Jun 2024 03:58:43 -0700 (PDT) Message-ID: <9ad3dcc8-0d13-4c57-8a93-6a96a8810960@redhat.com> Date: Thu, 13 Jun 2024 12:58:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 1/8] tcp: extract buffer management from tcp_send_flag() To: Stefano Brivio References: <20240612154734.1044883-1-lvivier@redhat.com> <20240612154734.1044883-2-lvivier@redhat.com> <20240612232210.3b1f975f@elisabeth> <20240613080719.67933d22@elisabeth> <20240613121415.4c92b62e@elisabeth> <79e33c3e-1194-4acb-b1ab-71d1ac6d94a7@redhat.com> <20240613124954.0134e128@elisabeth> From: Laurent Vivier Autocrypt: addr=lvivier@redhat.com; keydata= xsFNBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABzSNMYXVyZW50IFZp dmllciA8bHZpdmllckByZWRoYXQuY29tPsLBeAQTAQIAIgUCVgVQgAIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjwpgg//fSGy0Rs/t8cPFuzoY1cex4limJQfReLr SJXCANg9NOWy/bFK5wunj+h/RCFxIFhZcyXveurkBwYikDPUrBoBRoOJY/BHK0iZo7/WQkur 6H5losVZtrotmKOGnP/lJYZ3H6OWvXzdz8LL5hb3TvGOP68K8Bn8UsIaZJoeiKhaNR0sOJyI YYbgFQPWMHfVwHD/U+/gqRhD7apVysxv5by/pKDln1I5v0cRRH6hd8M8oXgKhF2+rAOL7gvh jEHSSWKUlMjC7YwwjSZmUkL+TQyE18e2XBk85X8Da3FznrLiHZFHQ/NzETYxRjnOzD7/kOVy gKD/o7asyWQVU65mh/ECrtjfhtCBSYmIIVkopoLaVJ/kEbVJQegT2P6NgERC/31kmTF69vn8 uQyW11Hk8tyubicByL3/XVBrq4jZdJW3cePNJbTNaT0d/bjMg5zCWHbMErUib2Nellnbg6bc 2HLDe0NLVPuRZhHUHM9hO/JNnHfvgiRQDh6loNOUnm9Iw2YiVgZNnT4soUehMZ7au8PwSl4I KYE4ulJ8RRiydN7fES3IZWmOPlyskp1QMQBD/w16o+lEtY6HSFEzsK3o0vuBRBVp2WKnssVH qeeV01ZHw0bvWKjxVNOksP98eJfWLfV9l9e7s6TaAeySKRRubtJ+21PRuYAxKsaueBfUE7ZT 7zfOwU0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5TGxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT 460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwvF8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BN efdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2NyHfmZlPGE0Nsy7hlebS4liisXOrN3jFz asKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqXGcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0 VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eophoWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFM C3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHKXWo+xf9WgtLeby3cfSkEchACrxDrQpj+ Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunTco1+cKSuRiSCYpBIXZMHCzPgVDjk4viP brV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCqkCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6 z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCmdNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JP jfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHBCzkM4rWyRhuVABEBAAHCwV8EGAECAAkF AlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtI WlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b6WimV64FmlVn17Ri6FgFU3xNt9TTEChq AcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2x OhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76J21YeRrEW4WDznPyVcDTa+tz++q2S/Bp P4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjXEYRWdiCxN7ca5iPml5gLtuvhJMSy36gl U6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2TxL8enfx40PrfbDtWwqRID3WY8jLrjKfTd R3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPM oDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyx FCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbLXiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsB kmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZD+Ofp0T3KOr1RUHvCZoLURfFhSQ= In-Reply-To: <20240613124954.0134e128@elisabeth> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Message-ID-Hash: ZYPSMSKE42O2RMCHI52HEGZOIMMV567Y X-Message-ID-Hash: ZYPSMSKE42O2RMCHI52HEGZOIMMV567Y X-MailFrom: lvivier@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top, David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 13/06/2024 12:49, Stefano Brivio wrote: > On Thu, 13 Jun 2024 12:22:54 +0200 > Laurent Vivier wrote: > >> On 13/06/2024 12:14, Stefano Brivio wrote: >>> On Thu, 13 Jun 2024 10:24:11 +0200 >>> Laurent Vivier wrote: >>> >>>> Hi, >>>> >>>> I think the problem can be because tcp_l2_buf_fill_headers() has been moved out of >>>> tcp_prepare_flags() and so moved after: >>>> >>>> if (th->fin || th->syn) >>>> conn->seq_to_tap++; >>>> >>>> and con->seq_to_tap is also a parameter of tcp_l2_buf_fill_headers(). So it is increased >>>> before and not after. >>>> >>>> Could you try: >>>> >>>> diff --git a/tcp.c b/tcp.c >>>> index 6800209d4122..647f42291fcf 100644 >>>> --- a/tcp.c >>>> +++ b/tcp.c >>>> @@ -1607,6 +1607,7 @@ static int tcp_prepare_flags(struct ctx *c, struct tcp_tap_conn *conn, >>>> if (!tcp_update_seqack_wnd(c, conn, flags, &tinfo) && !flags) >>>> return 0; >>>> >>>> + *optlen = 0; >>>> if (flags & SYN) { >>>> int mss; >>>> >>>> @@ -1643,7 +1644,6 @@ static int tcp_prepare_flags(struct ctx *c, struct tcp_tap_conn *conn, >>>> *data++ = conn->ws_to_tap; >>>> } else if (!(flags & RST)) { >>>> flags |= ACK; >>>> - *optlen = 0; >>>> } >>>> >>>> th->doff = (sizeof(*th) + *optlen) / 4; >>>> @@ -1663,10 +1663,6 @@ static int tcp_prepare_flags(struct ctx *c, struct tcp_tap_conn *conn, >>>> if (th->fin) >>>> conn_flag(c, conn, ACK_FROM_TAP_DUE); >>>> >>>> - /* RFC 793, 3.1: "[...] and the first data octet is ISN+1." */ >>>> - if (th->fin || th->syn) >>>> - conn->seq_to_tap++; >>>> - >>>> return 1; >>>> } >>>> >>>> @@ -1702,6 +1698,10 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, >>>> int flags) >>>> conn->seq_to_tap); >>>> iov[TCP_IOV_PAYLOAD].iov_len = l4len; >>>> >>>> + /* RFC 793, 3.1: "[...] and the first data octet is ISN+1." */ >>>> + if (th->fin || th->syn) >>>> + conn->seq_to_tap++; >>>> + >>>> if (flags & DUP_ACK) { >>>> struct iovec *dup_iov; >>>> int i; >>> >>> Ah, yes, good catch, I missed this one! It works. Note that it needs to >>> be: >>> >>> if ((flags & FIN) || (flags & SYN)) >>> ... >>> >>> because we don't have a TCP header there, yet. >>> >> >> I'm wondering if I can do: >> >> + seq = conn->seq_to_tap; >> ret = tcp_prepare_flags(c, conn, flags, &payload->th, >> payload->opts, &optlen); >> if (ret <= 0) >> return ret; >> >> l4len = tcp_l2_buf_fill_headers(c, conn, iov, optlen, NULL, >> - conn->seq_to_tap); >> + seq); >> >> to keep the flags in tcp_prepare_flags()? > > Maybe, yes. I don't really have a strong preference. On the other hand > tcp_send_flag() has to deal with the DUP_ACK case on its own anyway. > > But sure, this version would be a bit cleaner, and if vhost-user code > will then want to call tcp_prepare_flags() without tcp_send_flag(), > it avoids code duplication, I guess? > Yes. I prepare a new version of the series with the changes. Thanks, Laurent