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    Subject[PATCH 5.19 152/207] net/smc: Stop the CLC flow if no link to map buffers on
    Date
    From: Wen Gu <guwen@linux.alibaba.com>

    [ Upstream commit e738455b2c6dcdab03e45d97de36476f93f557d2 ]

    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>
    Link: https://lore.kernel.org/r/1663656189-32090-1-git-send-email-guwen@linux.alibaba.com
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 1f3bb1f6b1f7..8095876b66eb 100644
    --- a/net/smc/smc_core.c
    +++ b/net/smc/smc_core.c
    @@ -2148,7 +2148,7 @@ 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);
    @@ -2161,9 +2161,12 @@ 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;
    }

    --
    2.35.1


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