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SubjectRe: [PATCH net] net/smc: Stop the CLC flow if no link to map buffers on
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On 2022/9/20 14:43, Wen Gu wrote:

> There might be a potential race between SMC-R buffer map and
> link group termination.
>
> smc_smcr_terminate_all() | smc_connect_rdma()
> --------------------------------------------------------------
> | smc_conn_create()
> for links in smcibdev |
> schedule links down |
> | smc_buf_create()
> | \- smcr_buf_map_usable_links()
> | \- no usable links found,
> | (rmb->mr = NULL)
> |
> | smc_clc_send_confirm()
> | \- access conn->rmb_desc->mr[]->rkey
> | (panic)
>
> During reboot and IB device module remove, all links will be set
> down and no usable links remain in link groups. In such situation
> smcr_buf_map_usable_links() should return an error and stop the
> CLC flow accessing to uninitialized mr.
>
> Fixes: b9247544c1bc ("net/smc: convert static link ID instances to support multiple links")
> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> ---
> net/smc/smc_core.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
> index ebf56cd..df89c2e 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -2239,7 +2239,7 @@ static struct smc_buf_desc *smcr_new_buf_create(struct smc_link_group *lgr,
> static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
> struct smc_buf_desc *buf_desc, bool is_rmb)
> {
> - int i, rc = 0;
> + int i, rc = 0, cnt = 0;
>
> /* protect against parallel link reconfiguration */
> mutex_lock(&lgr->llc_conf_mutex);
> @@ -2252,9 +2252,12 @@ static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
> rc = -ENOMEM;
> goto out;
> }
> + cnt++;
> }
> out:
> mutex_unlock(&lgr->llc_conf_mutex);
> + if (!rc && !cnt)
> + rc = -EINVAL;
> return rc;
> }
>

Any comments or reviews are welcome and appreciated.

Thanks,
Wen Gu

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