From: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
[ Upstream commit 22a825c541d775c1dbe7b2402786025acad6727b ]
When performing a stress test on SMC-R by rmmod mlx5_ib driver
during the wrk/nginx test, we found that there is a probability
of triggering a panic while terminating all link groups.
This issue dues to the race between smc_smcr_terminate_all()
and smc_buf_create().
smc_smcr_terminate_all
smc_buf_create
/* init */
conn->sndbuf_desc = NULL;
...
__smc_lgr_terminate
smc_conn_kill
smc_close_abort
smc_cdc_get_slot_and_msg_send
__softirqentry_text_start
smc_wr_tx_process_cqe
smc_cdc_tx_handler
READ(conn->sndbuf_desc->len);
/* panic dues to NULL sndbuf_desc */
conn->sndbuf_desc = xxx;
This patch tries to fix the issue by always to check the sndbuf_desc
before send any cdc msg, to make sure that no null pointer is
seen during cqe processing.
Fixes: 0b29ec643613 ("net/smc: immediate termination for SMCR link groups")
Signed-off-by: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
Reviewed-by: Tony Lu <tonylu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Wenjia Zhang <wenjia@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1678263432-17329-1-git-send-email-alibuda@xxxxxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/smc/smc_cdc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 5d180d24cbf1c..41b23f71c29a2 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -104,6 +104,9 @@ int smc_cdc_msg_send(struct smc_connection *conn,
union smc_host_cursor cfed;
int rc;
+ if (unlikely(!READ_ONCE(conn->sndbuf_desc)))
+ return -ENOBUFS;
+
smc_cdc_add_pending_send(conn, pend);
conn->tx_cdc_seq++;
--
2.39.2
