On 8/26/21 7:16 AM, kerneljasonxing@xxxxxxxxx wrote:
> From: Jason Xing <xingwanli@xxxxxxxxxxxx>
>
> Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> server is equipped with more than 64 cpus online. So it turns out that
> the loading of xdpdrv causes the "NOMEM" failure.
>
> Actually, we can adjust the algorithm and then make it work through
> mapping the current cpu to some xdp ring with the protect of @tx_lock.
>
> v4:
> - Update the wrong commit messages. (Jason)
>
> v3:
> - Change nr_cpu_ids to num_online_cpus() (Maciej)
I suspect this is wrong.
> - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
>
> v2:
> - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> - Add a fallback path. (Maciej)
> - Adjust other parts related to xdp ring.
>
> Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> Co-developed-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Jason Xing <xingwanli@xxxxxxxxxxxx>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
> .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
> 5 files changed, 73 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> index a604552..5f7f181 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
> @@ -82,6 +82,8 @@
> #define IXGBE_2K_TOO_SMALL_WITH_PADDING \
> ((NET_SKB_PAD + IXGBE_RXBUFFER_1536) > SKB_WITH_OVERHEAD(IXGBE_RXBUFFER_2K))
>
> +DECLARE_STATIC_KEY_FALSE(ixgbe_xdp_locking_key);
> +
> static inline int ixgbe_compute_pad(int rx_buf_len)
> {
> int page_size, pad_size;
> @@ -351,6 +353,7 @@ struct ixgbe_ring {
> };
> u16 rx_offset;
> struct xdp_rxq_info xdp_rxq;
> + spinlock_t tx_lock; /* used in XDP mode */
> struct xsk_buff_pool *xsk_pool;
> u16 ring_idx; /* {rx,tx,xdp}_ring back reference idx */
> u16 rx_buf_len;
> @@ -375,7 +378,7 @@ enum ixgbe_ring_f_enum {
> #define IXGBE_MAX_FCOE_INDICES 8
> #define MAX_RX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> #define MAX_TX_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> -#define MAX_XDP_QUEUES (IXGBE_MAX_FDIR_INDICES + 1)
> +#define IXGBE_MAX_XDP_QS (IXGBE_MAX_FDIR_INDICES + 1)
> #define IXGBE_MAX_L2A_QUEUES 4
> #define IXGBE_BAD_L2A_QUEUE 3
> #define IXGBE_MAX_MACVLANS 63
> @@ -629,7 +632,7 @@ struct ixgbe_adapter {
>
> /* XDP */
> int num_xdp_queues;
> - struct ixgbe_ring *xdp_ring[MAX_XDP_QUEUES];
> + struct ixgbe_ring *xdp_ring[IXGBE_MAX_XDP_QS];
> unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled rings */
>
> /* TX */
> @@ -772,6 +775,14 @@ struct ixgbe_adapter {
> #endif /* CONFIG_IXGBE_IPSEC */
> };
>
> +static inline int ixgbe_determine_xdp_q_idx(int cpu)
> +{
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + return cpu % IXGBE_MAX_XDP_QS;
> + else
> + return cpu;
Even if num_online_cpus() is 8, the returned cpu here could be
0, 32, 64, 96, 128, 161, 197, 224
Are we sure this will still be ok ?
> +}
> +
> static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)
> {
> switch (adapter->hw.mac.type) {
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> index 0218f6c..884bf99 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
> @@ -299,7 +299,10 @@ static void ixgbe_cache_ring_register(struct ixgbe_adapter *adapter)
>
> static int ixgbe_xdp_queues(struct ixgbe_adapter *adapter)
> {
> - return adapter->xdp_prog ? nr_cpu_ids : 0;
> + int queues;
> +
> + queues = min_t(int, IXGBE_MAX_XDP_QS, num_online_cpus());
num_online_cpus() might change later...
> + return adapter->xdp_prog ? queues : 0;
> }
>
> #define IXGBE_RSS_64Q_MASK 0x3F
> @@ -947,6 +950,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
> ring->count = adapter->tx_ring_count;
> ring->queue_index = xdp_idx;
> set_ring_xdp(ring);
> + spin_lock_init(&ring->tx_lock);
>
> /* assign ring to adapter */
> WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);
> @@ -1032,6 +1036,9 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)
> adapter->q_vector[v_idx] = NULL;
> __netif_napi_del(&q_vector->napi);
>
> + if (static_key_enabled(&ixgbe_xdp_locking_key))
> + static_branch_dec(&ixgbe_xdp_locking_key);
> +
> /*
>
