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| author | Gerd Rausch <gerd.rausch@oracle.com> | 2026-02-02 22:57:17 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-02-04 20:46:38 -0800 |
| commit | a20a6992558fa7c19a03c76bea4a793ccaef8505 (patch) | |
| tree | 47dbe19a4966ddd150f03f607ef6bd027523756a /net/rds/rds.h | |
| parent | 46f257ee6904125e6336d63f0694ff4c491cfbf7 (diff) | |
| download | linux-next-a20a6992558fa7c19a03c76bea4a793ccaef8505.tar.gz linux-next-a20a6992558fa7c19a03c76bea4a793ccaef8505.zip | |
net/rds: Encode cp_index in TCP source port
Upon "sendmsg", RDS/TCP selects a backend connection based
on a hash calculated from the source-port ("RDS_MPATH_HASH").
However, "rds_tcp_accept_one" accepts connections
in the order they arrive, which is non-deterministic.
Therefore the mapping of the sender's "cp->cp_index"
to that of the receiver changes if the backend
connections are dropped and reconnected.
However, connection state that's preserved across reconnects
(e.g. "cp_next_rx_seq") relies on that sender<->receiver
mapping to never change.
So we make sure that client and server of the TCP connection
have the exact same "cp->cp_index" across reconnects by
encoding "cp->cp_index" in the lower three bits of the
client's TCP source port.
A new extension "RDS_EXTHDR_SPORT_IDX" is introduced,
that allows the server to tell the difference between
clients that do the "cp->cp_index" encoding, and
legacy clients that pick source ports randomly.
Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Link: https://patch.msgid.link/20260203055723.1085751-3-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/rds/rds.h')
| -rw-r--r-- | net/rds/rds.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/rds/rds.h b/net/rds/rds.h index 4b6bf523b412..5b5fb53b1fc5 100644 --- a/net/rds/rds.h +++ b/net/rds/rds.h @@ -147,6 +147,7 @@ struct rds_connection { c_ping_triggered:1, c_pad_to_32:29; int c_npaths; + bool c_with_sport_idx; struct rds_connection *c_passive; struct rds_transport *c_trans; @@ -278,8 +279,10 @@ struct rds_ext_header_rdma_bytes { */ #define RDS_EXTHDR_NPATHS 5 #define RDS_EXTHDR_GEN_NUM 6 +#define RDS_EXTHDR_SPORT_IDX 8 #define __RDS_EXTHDR_MAX 16 /* for now */ + #define RDS_RX_MAX_TRACES (RDS_MSG_RX_DGRAM_TRACE_MAX + 1) #define RDS_MSG_RX_HDR 0 #define RDS_MSG_RX_START 1 |