From: D. Wythe alibuda@linux.alibaba.com
[ 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@linux.alibaba.com Reviewed-by: Tony Lu tonylu@linux.alibaba.com Reviewed-by: Wenjia Zhang wenjia@linux.ibm.com Link: https://lore.kernel.org/r/1678263432-17329-1-git-send-email-alibuda@linux.al... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 53f63bfbaf5f9..89105e95b4523 100644 --- a/net/smc/smc_cdc.c +++ b/net/smc/smc_cdc.c @@ -114,6 +114,9 @@ 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++;