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Wed, 27 Oct 2021 10:21:21 +0000 (GMT) Message-ID: <9bbd05ac-5fa5-7d7a-fe69-e7e072ccd1ab@linux.ibm.com> Date: Wed, 27 Oct 2021 12:21:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH net 1/4] Revert "net/smc: don't wait for send buffer space when data was already sent" Content-Language: en-US To: Tony Lu , davem@davemloft.net, kuba@kernel.org Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, jacob.qi@linux.alibaba.com, xuanzhuo@linux.alibaba.com, guwen@linux.alibaba.com, dust.li@linux.alibaba.com References: <20211027085208.16048-1-tonylu@linux.alibaba.com> <20211027085208.16048-2-tonylu@linux.alibaba.com> From: Karsten Graul Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20211027085208.16048-2-tonylu@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Kcyctn3wA8Ob1waKbS0LKwy4cYZoWaiX X-Proofpoint-ORIG-GUID: How5wNOuaxRx9plDTr7zIq0Q3NU9HMnI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-10-27_03,2021-10-26_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 phishscore=0 priorityscore=1501 lowpriorityscore=0 impostorscore=0 mlxscore=0 suspectscore=0 spamscore=0 malwarescore=0 adultscore=0 bulkscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2110270062 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 27/10/2021 10:52, Tony Lu wrote: > From: Tony Lu > > This reverts commit 6889b36da78a21a312d8b462c1fa25a03c2ff192. > > When using SMC to replace TCP, some userspace applications like netperf > don't check the return code of send syscall correctly, which means how > many bytes are sent. If rc of send() is smaller than expected, it should > try to send again, instead of exit directly. It is difficult to change > the uncorrect behaviors of userspace applications, so choose to revert it. Your change would restore the old behavior to handle all sockets like they are blocking sockets, trying forever to send the provided data bytes. This is not how it should work. We encountered the same issue with netperf, but this is the only 'broken' application that we know of so far which does not implement the socket API correctly.