linux/net/smc
D. Wythe e6d71b437a net/smc: avoid data corruption caused by decline
We found a data corruption issue during testing of SMC-R on Redis
applications.

The benchmark has a low probability of reporting a strange error as
shown below.

"Error: Protocol error, got "\xe2" as reply type byte"

Finally, we found that the retrieved error data was as follows:

0xE2 0xD4 0xC3 0xD9 0x04 0x00 0x2C 0x20 0xA6 0x56 0x00 0x16 0x3E 0x0C
0xCB 0x04 0x02 0x01 0x00 0x00 0x20 0x00 0x00 0x00 0x00 0x00 0x00 0x00
0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xE2

It is quite obvious that this is a SMC DECLINE message, which means that
the applications received SMC protocol message.
We found that this was caused by the following situations:

client                  server
        ¦  clc proposal
        ------------->
        ¦  clc accept
        <-------------
        ¦  clc confirm
        ------------->
wait llc confirm
			send llc confirm
        ¦failed llc confirm
        ¦   x------
(after 2s)timeout
                        wait llc confirm rsp

wait decline

(after 1s) timeout
                        (after 2s) timeout
        ¦   decline
        -------------->
        ¦   decline
        <--------------

As a result, a decline message was sent in the implementation, and this
message was read from TCP by the already-fallback connection.

This patch double the client timeout as 2x of the server value,
With this simple change, the Decline messages should never cross or
collide (during Confirm link timeout).

This issue requires an immediate solution, since the protocol updates
involve a more long-term solution.

Fixes: 0fb0b02bd6 ("net/smc: adapt SMC client code to use the LLC flow")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-11-22 12:10:19 +00:00
..
af_smc.c net/smc: avoid data corruption caused by decline 2023-11-22 12:10:19 +00:00
Kconfig net/smc: Fix dependency of SMC on ISM 2023-10-10 11:51:41 +02:00
Makefile net/smc: fix compile warning for smc_sysctl 2022-03-07 11:59:17 +00:00
smc_cdc.c net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc 2023-11-06 10:01:07 +00:00
smc_cdc.h net/smc: fix kernel panic caused by race of smc_sock 2021-12-28 12:42:45 +00:00
smc_clc.c net/smc: support max links per lgr negotiation in clc handshake 2023-08-19 12:46:53 +01:00
smc_clc.h net/smc: support max links per lgr negotiation in clc handshake 2023-08-19 12:46:53 +01:00
smc_close.c net/smc: put sk reference if close work was canceled 2023-11-06 10:01:07 +00:00
smc_close.h
smc_core.c net/smc: use smc_lgr_list.lock to protect smc_lgr_list.list iterate in smcr_port_add 2023-09-10 19:31:42 +01:00
smc_core.h net/smc: support max links per lgr negotiation in clc handshake 2023-08-19 12:46:53 +01:00
smc_diag.c net: fill in MODULE_DESCRIPTION()s for SOCK_DIAG modules 2023-11-19 20:09:13 +00:00
smc_ib.c net/smc: fix smc clc failed issue when netdevice not in init_net 2023-10-13 16:52:02 -07:00
smc_ib.h net/smc: fix smc clc failed issue when netdevice not in init_net 2023-10-13 16:52:02 -07:00
smc_ism.c net/smc: Introduce explicit check for v2 support 2023-03-15 08:18:35 +00:00
smc_ism.h net/smc: Register SMC-D as ISM client 2023-01-25 09:46:48 +00:00
smc_llc.c net/smc: support max links per lgr negotiation in clc handshake 2023-08-19 12:46:53 +01:00
smc_llc.h net/smc: Introduce a specific sysctl for TEST_LINK time 2022-09-22 12:58:21 +02:00
smc_netlink.c genetlink: start to validate reserved header bytes 2022-08-29 12:47:15 +01:00
smc_netlink.h
smc_netns.h
smc_pnet.c net/smc: De-tangle ism and smc device initialization 2023-01-25 09:46:49 +00:00
smc_pnet.h net/smc: Use a mutex for locking "struct smc_pnettable" 2022-02-24 09:09:33 -08:00
smc_rx.c net: deal with most data-races in sk_wait_event() 2023-05-10 10:03:32 +01:00
smc_rx.h
smc_stats.c smc: Drop smc_sendpage() in favour of smc_sendmsg() + MSG_SPLICE_PAGES 2023-06-24 15:50:12 -07:00
smc_stats.h net/smc: Fix pos miscalculation in statistics 2023-10-11 10:36:35 +01:00
smc_sysctl.c sysctl-6.6-rc1 2023-08-29 17:39:15 -07:00
smc_sysctl.h net/smc: fix -Wmissing-prototypes warning when CONFIG_SYSCTL not set 2022-03-09 20:02:35 -08:00
smc_tracepoint.c net/smc: Introduce tracepoint for smcr link down 2021-11-01 13:39:14 +00:00
smc_tracepoint.h net/smc: Add net namespace for tracepoints 2022-01-02 12:07:39 +00:00
smc_tx.c smc: Drop smc_sendpage() in favour of smc_sendmsg() + MSG_SPLICE_PAGES 2023-06-24 15:50:12 -07:00
smc_tx.h smc: Drop smc_sendpage() in favour of smc_sendmsg() + MSG_SPLICE_PAGES 2023-06-24 15:50:12 -07:00
smc_wr.c net/smc: Use percpu ref for wr tx reference 2023-03-17 08:59:01 +00:00
smc_wr.h net/smc: Use percpu ref for wr tx reference 2023-03-17 08:59:01 +00:00
smc.h net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT 2023-11-06 10:01:07 +00:00