netdev - [PATCH net 1/2] net/smc: initialize close

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Message-Id: <20241122071630.63707-2-guwen@linux.alibaba.com>
Date: Fri, 22 Nov 2024 15:16:29 +0800
From: Wen Gu <guwen@...ux.alibaba.com>
To: wenjia@...ux.ibm.com,
	jaka@...ux.ibm.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: alibuda@...ux.alibaba.com,
	tonylu@...ux.alibaba.com,
	guwen@...ux.alibaba.com,
	horms@...nel.org,
	linux-rdma@...r.kernel.org,
	linux-s390@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net 1/2] net/smc: initialize close_work early to avoid warning

We encountered a warning that close_work was canceled before
initialization.

  WARNING: CPU: 7 PID: 111103 at kernel/workqueue.c:3047 __flush_work+0x19e/0x1b0
  Workqueue: events smc_lgr_terminate_work [smc]
  RIP: 0010:__flush_work+0x19e/0x1b0
  Call Trace:
   ? __wake_up_common+0x7a/0x190
   ? work_busy+0x80/0x80
   __cancel_work_timer+0xe3/0x160
   smc_close_cancel_work+0x1a/0x70 [smc]
   smc_close_active_abort+0x207/0x360 [smc]
   __smc_lgr_terminate.part.38+0xc8/0x180 [smc]
   process_one_work+0x19e/0x340
   worker_thread+0x30/0x370
   ? process_one_work+0x340/0x340
   kthread+0x117/0x130
   ? __kthread_cancel_work+0x50/0x50
   ret_from_fork+0x22/0x30

This is because when smc_close_cancel_work is triggered, e.g. the RDMA
driver is rmmod and the LGR is terminated, the conn->close_work is
flushed before initialization, resulting in WARN_ON(!work->func).

__smc_lgr_terminate             | smc_connect_{rdma|ism}
-------------------------------------------------------------
                                | smc_conn_create
				| \- smc_lgr_register_conn
for conn in lgr->conns_all      |
\- smc_conn_kill                |
   \- smc_close_active_abort    |
      \- smc_close_cancel_work  |
         \- cancel_work_sync    |
            \- __flush_work     |
	         (close_work)   |
	                        | smc_close_init
	                        | \- INIT_WORK(&close_work)

So fix this by initializing close_work before establishing the
connection.

Fixes: 46c28dbd4c23 ("net/smc: no socket state changes in tasklet context")
Fixes: 413498440e30 ("net/smc: add SMC-D support in af_smc")
Signed-off-by: Wen Gu <guwen@...ux.alibaba.com>
---
 net/smc/af_smc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 9d76e902fd77..ed6d4d520bc7 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -383,6 +383,7 @@ void smc_sk_init(struct net *net, struct sock *sk, int protocol)
 	smc->limit_smc_hs = net->smc.limit_smc_hs;
 	smc->use_fallback = false; /* assume rdma capability first */
 	smc->fallback_rsn = 0;
+	smc_close_init(smc);
 }
 
 static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
@@ -1299,7 +1300,6 @@ static int smc_connect_rdma(struct smc_sock *smc,
 		goto connect_abort;
 	}
 
-	smc_close_init(smc);
 	smc_rx_init(smc);
 
 	if (ini->first_contact_local) {
@@ -1435,7 +1435,6 @@ static int smc_connect_ism(struct smc_sock *smc,
 			goto connect_abort;
 		}
 	}
-	smc_close_init(smc);
 	smc_rx_init(smc);
 	smc_tx_init(smc);
 
@@ -2479,7 +2478,6 @@ static void smc_listen_work(struct work_struct *work)
 		goto out_decl;
 
 	mutex_lock(&smc_server_lgr_pending);
-	smc_close_init(new_smc);
 	smc_rx_init(new_smc);
 	smc_tx_init(new_smc);
 
-- 
2.32.0.3.g01195cf9f