> Subject: [PATCH net-next v2 1/4] net: mana: Fix potential deadlocks in mana
> napi
> ops
>
> When net_shaper_ops are enabled for MANA, netdev_ops_lock becomes active.
>
> MANA VF setup/teardown by netvsc follows this call chain:
>
> netvsc_vf_setup()
> dev_change_flags()
> ...
> __dev_open() OR __dev_close()
>
> dev_change_flags() holds the netdev mutex via netdev_lock_ops.
>
> Meanwhile, mana_create_txq() and mana_create_rxq() in mana_open() path call
> NAPI APIs (netif_napi_add_tx(), netif_napi_add_weight(), napi_enable()), which
> also try to acquire the same lock, risking deadlock.
>
> Similarly in the teardown path (mana_close()), netif_napi_disable() and
> netif_napi_del(), contend for the same lock.
>
> Switch to the _locked variants of these APIs to avoid deadlocks when the
> netdev_ops_lock is held.
>
> Fixes: d4c22ec680c8 ("net: hold netdev instance lock during
> ndo_open/ndo_stop")
> Signed-off-by: Erni Sri Satya Vennela <er...@linux.microsoft.com>
> Reviewed-by: Haiyang Zhang <haiya...@microsoft.com>
> Reviewed-by: Shradha Gupta <shradhagu...@linux.microsoft.com>
> Reviewed-by: Saurabh Singh Sengar <ssen...@linux.microsoft.com>
Reviewed-by: Long Li <lon...@microsoft.com>
> ---
> Changes in v2:
> * Use netdev_lock_ops_to_full() instead of if...else statements for napi
> APIs.
> * Edit commit message.
> ---
> drivers/net/ethernet/microsoft/mana/mana_en.c | 30 +++++++++++++------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index e68b8190bb7a..ca5e9c3d374b 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -1912,8 +1912,11 @@ static void mana_destroy_txq(struct
> mana_port_context *apc)
> napi = &apc->tx_qp[i].tx_cq.napi;
> if (apc->tx_qp[i].txq.napi_initialized) {
> napi_synchronize(napi);
> - napi_disable(napi);
> - netif_napi_del(napi);
> + netdev_lock_ops_to_full(napi->dev);
> + napi_disable_locked(napi);
> + netif_napi_del_locked(napi);
> + netdev_unlock_full_to_ops(napi->dev);
> apc->tx_qp[i].txq.napi_initialized = false;
> }
> mana_destroy_wq_obj(apc, GDMA_SQ, apc-
> >tx_qp[i].tx_object); @@ -2065,8 +2068,11 @@ static int
> mana_create_txq(struct mana_port_context *apc,
>
> mana_create_txq_debugfs(apc, i);
>
> - netif_napi_add_tx(net, &cq->napi, mana_poll);
> - napi_enable(&cq->napi);
> + set_bit(NAPI_STATE_NO_BUSY_POLL, &cq->napi.state);
> + netdev_lock_ops_to_full(net);
> + netif_napi_add_locked(net, &cq->napi, mana_poll);
> + napi_enable_locked(&cq->napi);
> + netdev_unlock_full_to_ops(net);
> txq->napi_initialized = true;
>
> mana_gd_ring_cq(cq->gdma_cq, SET_ARM_BIT); @@ -2102,9
> +2108,11 @@ static void mana_destroy_rxq(struct mana_port_context *apc,
> if (napi_initialized) {
> napi_synchronize(napi);
>
> - napi_disable(napi);
> -
> - netif_napi_del(napi);
> + netdev_lock_ops_to_full(napi->dev);
> + napi_disable_locked(napi);
> + netif_napi_del_locked(napi);
> + netdev_unlock_full_to_ops(napi->dev);
> }
> xdp_rxq_info_unreg(&rxq->xdp_rxq);
>
> @@ -2355,14 +2363,18 @@ static struct mana_rxq *mana_create_rxq(struct
> mana_port_context *apc,
>
> gc->cq_table[cq->gdma_id] = cq->gdma_cq;
>
> - netif_napi_add_weight(ndev, &cq->napi, mana_poll, 1);
> + netdev_lock_ops_to_full(ndev);
> + netif_napi_add_weight_locked(ndev, &cq->napi, mana_poll, 1);
> + netdev_unlock_full_to_ops(ndev);
>
> WARN_ON(xdp_rxq_info_reg(&rxq->xdp_rxq, ndev, rxq_idx,
> cq->napi.napi_id));
> WARN_ON(xdp_rxq_info_reg_mem_model(&rxq->xdp_rxq,
> MEM_TYPE_PAGE_POOL,
> rxq->page_pool));
>
> - napi_enable(&cq->napi);
> + netdev_lock_ops_to_full(ndev);
> + napi_enable_locked(&cq->napi);
> + netdev_unlock_full_to_ops(ndev);
>
> mana_gd_ring_cq(cq->gdma_cq, SET_ARM_BIT);
> out:
> --
> 2.34.1
