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Wythe" , Dust Li , Sidraya Jayagond , Wenjia Zhang , Julian Ruess Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thorsten Winkler , Simon Horman , Mahanta Jambigi , Tony Lu , Wen Gu , Halil Pasic , linux-rdma@vger.kernel.org Subject: [RFC net-next 04/17] net/smc: Decouple sf and attached send_buf in smc_loopback Date: Wed, 6 Aug 2025 17:41:09 +0200 Message-ID: <20250806154122.3413330-5-wintera@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250806154122.3413330-1-wintera@linux.ibm.com> References: <20250806154122.3413330-1-wintera@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: jyiTIRE4q0zsVp7G99KTf-y14YpYVk8m X-Proofpoint-ORIG-GUID: Y9YAv8YJRO4kP32X7nvjy5LKqqaXFlT_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA2MDA5NiBTYWx0ZWRfX5pFydr3Z7p4N 6/AV3AJ981+anwzrBmpcxUwYNH00Dzlr0hIrmIQgZmBMWqK38lEM8KpRQ+tyWKd2sW6SOMl+jSj +sBcOuw8fV+o7G96RBP8Llt94X6y85PspXYoYQtilno9jb5qTTmgIcEuXG/28Gk0qoPoTl6BU85 7Ssan1fhqoEf6sfEaE8c5BRHN3GUf2fPhgThorSjtWlu/IVF5MBQxrsxIxY/jXzm7A7AyRPH8PH ZrSyTBGJrY2IvvMWmRHg2/CrfMXDbd+Ce4ZORxvYEoy8ZnXwZs2g0ig3c65+WoCCdZVGjrfHZrU qfNI8ybL83jLTWO0ftPQHZtxVxRhsATGSC60VIdzbhxtXthdfALAEIIxs6obKS6RmSgUTxh7jJD lqwJp5l0AKqxtD6stogmEqj4mTDamsKfXQmPBZJWkVDkI0qF/hQ9347iHWsn1fpqHVOjjPAA X-Authority-Analysis: v=2.4 cv=TayWtQQh c=1 sm=1 tr=0 ts=689377a8 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=2OwXVqhp2XgA:10 a=VnNF1IyMAAAA:8 a=YPWO3w2s4X-KU5j4784A:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-06_04,2025-08-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 phishscore=0 impostorscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508060096 Before this patch there was the following assumption in smc_loopback.c>smc_lo_move_data(): sf (signalling flag) == 0 : data is already in an attached target dmb sf == 1 : data is not yet in the target dmb This is true for the 2 callers in smc client smcd_cdc_msg_send() : sf=1 smcd_tx_rdma_writes() : sf=0 but should not be a general assumption. Add a bool to struct smc_buf_desc to indicate whether an SMC-D sndbuf_desc is an attached buffer. Don't call move_data() for attached send_buffers, because it is not necessary. Move the data in smc_lo_move_data() if len != 0 and signal when requested. Signed-off-by: Alexandra Winter Reviewed-by: Mahanta Jambigi --- net/smc/smc_core.h | 5 +++++ net/smc/smc_ism.c | 1 + net/smc/smc_loopback.c | 9 +++------ net/smc/smc_tx.c | 3 +++ 4 files changed, 12 insertions(+), 6 deletions(-) diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h index 48a1b1dcb576..fe5f48d14323 100644 --- a/net/smc/smc_core.h +++ b/net/smc/smc_core.h @@ -13,6 +13,7 @@ #define _SMC_CORE_H #include +#include #include #include #include @@ -221,12 +222,16 @@ struct smc_buf_desc { /* virtually contiguous */ }; struct { /* SMC-D */ + /* SMC-D rx buffer: */ unsigned short sba_idx; /* SBA index number */ u64 token; /* DMB token number */ dma_addr_t dma_addr; /* DMA address */ + /* SMC-D tx buffer */ + bool is_attached; + /* no need for explicit writes */ }; }; }; diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c index a94e1450d095..7363f8be9f94 100644 --- a/net/smc/smc_ism.c +++ b/net/smc/smc_ism.c @@ -274,6 +274,7 @@ int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token, dmb_desc->cpu_addr = dmb.cpu_addr; dmb_desc->dma_addr = dmb.dma_addr; dmb_desc->len = dmb.dmb_len; + dmb_desc->is_attached = true; } return rc; } diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c index 0eb00bbefd17..1853c26fbbbb 100644 --- a/net/smc/smc_loopback.c +++ b/net/smc/smc_loopback.c @@ -224,12 +224,6 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok, struct smc_lo_dev *ldev = smcd->priv; struct smc_connection *conn; - if (!sf) - /* since sndbuf is merged with peer DMB, there is - * no need to copy data from sndbuf to peer DMB. - */ - return 0; - read_lock_bh(&ldev->dmb_ht_lock); hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) { if (tmp_node->token == dmb_tok) { @@ -244,6 +238,9 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok, memcpy((char *)rmb_node->cpu_addr + offset, data, size); read_unlock_bh(&ldev->dmb_ht_lock); + if (!sf) + return 0; + conn = smcd->conn[rmb_node->sba_idx]; if (!conn || conn->killed) return -EPIPE; diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c index 214ac3cbcf9a..3144b4b1fe29 100644 --- a/net/smc/smc_tx.c +++ b/net/smc/smc_tx.c @@ -426,6 +426,9 @@ static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len, int srcchunk, dstchunk; int rc; + if (conn->sndbuf_desc->is_attached) + return 0; + for (dstchunk = 0; dstchunk < 2; dstchunk++) { for (srcchunk = 0; srcchunk < 2; srcchunk++) { void *data = conn->sndbuf_desc->cpu_addr + src_off; -- 2.48.1