Hi,
On Wed, May 06, 2020 at 02:24:39PM +0300, Paul Blakey wrote:
> Gc step can queue offloaded flow del work or stats work.
> Those work items can race each other and a flow could be freed
> before the stats work is executed and querying it.
> To avoid that, add a pending bit that if a work exists for a flow
> don't queue another work for it.
> This will also avoid adding multiple stats works in case stats work
> didn't complete but gc step started again.
This is happening since the mutex has been removed, right?
Another question below.
> Signed-off-by: Paul Blakey <paulb@xxxxxxxxxxxx>
> Reviewed-by: Roi Dayan <roid@xxxxxxxxxxxx>
> ---
> include/net/netfilter/nf_flow_table.h | 1 +
> net/netfilter/nf_flow_table_offload.c | 8 +++++++-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
> index 6bf6965..c54a7f7 100644
> --- a/include/net/netfilter/nf_flow_table.h
> +++ b/include/net/netfilter/nf_flow_table.h
> @@ -127,6 +127,7 @@ enum nf_flow_flags {
> NF_FLOW_HW_DYING,
> NF_FLOW_HW_DEAD,
> NF_FLOW_HW_REFRESH,
> + NF_FLOW_HW_PENDING,
> };
>
> enum flow_offload_type {
> diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
> index b9d5ecc..731d738 100644
> --- a/net/netfilter/nf_flow_table_offload.c
> +++ b/net/netfilter/nf_flow_table_offload.c
> @@ -817,6 +817,7 @@ static void flow_offload_work_handler(struct work_struct *work)
> WARN_ON_ONCE(1);
> }
>
> + clear_bit(NF_FLOW_HW_PENDING, &offload->flow->flags);
> kfree(offload);
> }
>
> @@ -831,9 +832,14 @@ static void flow_offload_queue_work(struct flow_offload_work *offload)
> {
> struct flow_offload_work *offload;
>
> + if (test_and_set_bit(NF_FLOW_HW_PENDING, &flow->flags))
> + return NULL;
In case of stats, it's fine to lose work.
But how does this work for the deletion case? Does this falls back to
the timeout deletion?
Thanks.
