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SubjectRe: [PATCH] RDMA/cm: fix cond_no_effect.cocci warnings
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On 6/10/2022 5:45 PM, Jiapeng Chong wrote:
> This was found by coccicheck:
>
> ./drivers/infiniband/core/cm.c:685:7-9: WARNING: possible condition with no effect (if == else).
>
> Reported-by: Abaci Robot <abaci@linux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
> ---
> drivers/infiniband/core/cm.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> index 1c107d6d03b9..bb6a2b6b9657 100644
> --- a/drivers/infiniband/core/cm.c
> +++ b/drivers/infiniband/core/cm.c
> @@ -676,14 +676,9 @@ static struct cm_id_private *cm_find_listen(struct ib_device *device,
> refcount_inc(&cm_id_priv->refcount);
> return cm_id_priv;
> }
> - if (device < cm_id_priv->id.device)
> + if (device < cm_id_priv->id.device ||
> + be64_lt(service_id, cm_id_priv->id.service_id))
> node = node->rb_left;
> - else if (device > cm_id_priv->id.device)
> - node = node->rb_right;
> - else if (be64_lt(service_id, cm_id_priv->id.service_id))
> - node = node->rb_left;
> - else if (be64_gt(service_id, cm_id_priv->id.service_id))
> - node = node->rb_right;
> else
> node = node->rb_right;
> }

Not sure if the fix is correct, e.g. with this condition:
device > cm_id_priv->id.device &&
be64_lt(service_id, cm_id_priv->id.service_id)

The original code gets rb_right but this fix gets rb_left. Maybe the
warning is complain about this:
...
else if (be64_gt(service_id, cm_id_priv->id.service_id))
node = node->rb_right;
else
node = node->rb_right;

Besides cm_insert_listen() has same logic.

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