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Message-ID: <6520c574-e1c6-49e0-8bb1-760032faaf7a@linux.alibaba.com>
Date: Wed, 17 Apr 2024 16:00:01 +0800
From: Guangguan Wang <guangguan.wang@...ux.alibaba.com>
To: Zhengchao Shao <shaozhengchao@...wei.com>, linux-s390@...r.kernel.org,
netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com
Cc: wenjia@...ux.ibm.com, jaka@...ux.ibm.com, alibuda@...ux.alibaba.com,
tonylu@...ux.alibaba.com, guwen@...ux.alibaba.com, weiyongjun1@...wei.com,
yuehaibing@...wei.com, tangchengchang@...wei.com
Subject: Re: [PATCH net] net/smc: fix potential sleeping issue in
smc_switch_conns
On 2024/4/13 11:51, Zhengchao Shao wrote:
> Potential sleeping issue exists in the following processes:
> smc_switch_conns
> spin_lock_bh(&conn->send_lock)
> smc_switch_link_and_count
> smcr_link_put
> __smcr_link_clear
> smc_lgr_put
> __smc_lgr_free
> smc_lgr_free_bufs
> __smc_lgr_free_bufs
> smc_buf_free
> smcr_buf_free
> smcr_buf_unmap_link
> smc_ib_put_memory_region
> ib_dereg_mr
> ib_dereg_mr_user
> mr->device->ops.dereg_mr
> If scheduling exists when the IB driver implements .dereg_mr hook
> function, the bug "scheduling while atomic" will occur. For example,
> cxgb4 and efa driver. Use mutex lock instead of spin lock to fix it.
>
> Fixes: 20c9398d3309 ("net/smc: Resolve the race between SMC-R link access and clear")
> Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
> ---
> net/smc/af_smc.c | 2 +-
> net/smc/smc.h | 2 +-
> net/smc/smc_cdc.c | 14 +++++++-------
> net/smc/smc_core.c | 8 ++++----
> net/smc/smc_tx.c | 8 ++++----
> 5 files changed, 17 insertions(+), 17 deletions(-)
>
Hi Zhengchao,
I doubt whether this bug really exists, as efa supports SRD QP while SMC-R relies on RC QP,
cxgb4 is a IWARP adaptor while SMC-R relies on ROCE adaptor.
Thanks,
Guangguan Wang
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