Re: [PATCH net 1/2] net/smc: initialize close_work early to avoid warning

Alexandra Winter
2024-11-22T16:17:11Z

On 22.11.24 08:16, Wen Gu wrote:
> 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@linux.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);
>

Thank you for the very good commit message. Makes sense to me.

Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>