linux-kernel - Re: [PATCH net 1/2] net/smc: initialize close

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Message-ID: <faba3530-c5f9-48af-be80-3847aa4921b7@linux.ibm.com>
Date: Fri, 22 Nov 2024 16:56:25 +0100
From: Wenjia Zhang <wenjia@...ux.ibm.com>
To: Wen Gu <guwen@...ux.alibaba.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, horms@...nel.org,
        linux-rdma@...r.kernel.org, linux-s390@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 1/2] net/smc: initialize close_work early to avoid
 warning



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@...ux.alibaba.com>
> ---

It looks plausible to me. Thank you for fixing it!

Reviewed-by: Wenjia Zhang <wenjia@...ux.ibm.com>

Thanks,
Wenjia