[PATCH] net/mlx5e: fix high stack usage

Arnd Bergmann
2018-11-02T15:33:03Z

A patch that looks harmless causes the stack usage of the mlx5e_grp_sw_update_stats()
function to drastically increase with x86 gcc-4.9 and higher (tested up to 8.1):

drivers/net/ethernet/mellanox/mlx5/core/en_stats.c: In function ‘mlx5e_grp_sw_update_stats’:
drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:216:1: warning: the frame size of 1276 bytes is larger than 500 bytes [-Wframe-larger-than=]

By splitting out the loop body into a non-inlined function, the stack size goes
back down to under 500 bytes.

Fixes: 779d986d60de ("net/mlx5e: Do not ignore netdevice TX/RX queues number")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
.../ethernet/mellanox/mlx5/core/en_stats.c | 168 +++++++++---------
1 file changed, 86 insertions(+), 82 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
index 1e55b9c27ffc..c270206f3475 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
@@ -126,93 +126,97 @@ static int mlx5e_grp_sw_fill_stats(struct mlx5e_priv *priv, u64 *data, int idx)
return idx;
}

+static noinline_for_stack void
+mlx5e_grp_sw_collect_stat(struct mlx5e_priv *priv, struct mlx5e_sw_stats *s, int i)
+{
+ struct mlx5e_channel_stats *channel_stats = &priv->channel_stats[i];
+ struct mlx5e_xdpsq_stats *xdpsq_red_stats = &channel_stats->xdpsq;
+ struct mlx5e_xdpsq_stats *xdpsq_stats = &channel_stats->rq_xdpsq;
+ struct mlx5e_rq_stats *rq_stats = &channel_stats->rq;
+ struct mlx5e_ch_stats *ch_stats = &channel_stats->ch;
+ int j;
+
+ s->rx_packets += rq_stats->packets;
+ s->rx_bytes += rq_stats->bytes;
+ s->rx_lro_packets += rq_stats->lro_packets;
+ s->rx_lro_bytes += rq_stats->lro_bytes;
+ s->rx_ecn_mark += rq_stats->ecn_mark;
+ s->rx_removed_vlan_packets += rq_stats->removed_vlan_packets;
+ s->rx_csum_none += rq_stats->csum_none;
+ s->rx_csum_complete += rq_stats->csum_complete;
+ s->rx_csum_unnecessary += rq_stats->csum_unnecessary;
+ s->rx_csum_unnecessary_inner += rq_stats->csum_unnecessary_inner;
+ s->rx_xdp_drop += rq_stats->xdp_drop;
+ s->rx_xdp_redirect += rq_stats->xdp_redirect;
+ s->rx_xdp_tx_xmit += xdpsq_stats->xmit;
+ s->rx_xdp_tx_full += xdpsq_stats->full;
+ s->rx_xdp_tx_err += xdpsq_stats->err;
+ s->rx_xdp_tx_cqe += xdpsq_stats->cqes;
+ s->rx_wqe_err += rq_stats->wqe_err;
+ s->rx_mpwqe_filler_cqes += rq_stats->mpwqe_filler_cqes;
+ s->rx_mpwqe_filler_strides += rq_stats->mpwqe_filler_strides;
+ s->rx_buff_alloc_err += rq_stats->buff_alloc_err;
+ s->rx_cqe_compress_blks += rq_stats->cqe_compress_blks;
+ s->rx_cqe_compress_pkts += rq_stats->cqe_compress_pkts;
+ s->rx_page_reuse += rq_stats->page_reuse;
+ s->rx_cache_reuse += rq_stats->cache_reuse;
+ s->rx_cache_full += rq_stats->cache_full;
+ s->rx_cache_empty += rq_stats->cache_empty;
+ s->rx_cache_busy += rq_stats->cache_busy;
+ s->rx_cache_waive += rq_stats->cache_waive;
+ s->rx_congst_umr += rq_stats->congst_umr;
+ s->rx_arfs_err += rq_stats->arfs_err;
+ s->ch_events += ch_stats->events;
+ s->ch_poll += ch_stats->poll;
+ s->ch_arm += ch_stats->arm;
+ s->ch_aff_change += ch_stats->aff_change;
+ s->ch_eq_rearm += ch_stats->eq_rearm;
+ /* xdp redirect */
+ s->tx_xdp_xmit += xdpsq_red_stats->xmit;
+ s->tx_xdp_full += xdpsq_red_stats->full;
+ s->tx_xdp_err += xdpsq_red_stats->err;
+ s->tx_xdp_cqes += xdpsq_red_stats->cqes;
+
+ for (j = 0; j < priv->max_opened_tc; j++) {
+ struct mlx5e_sq_stats *sq_stats = &channel_stats->sq[j];
+
+ s->tx_packets += sq_stats->packets;
+ s->tx_bytes += sq_stats->bytes;
+ s->tx_tso_packets += sq_stats->tso_packets;
+ s->tx_tso_bytes += sq_stats->tso_bytes;
+ s->tx_tso_inner_packets += sq_stats->tso_inner_packets;
+ s->tx_tso_inner_bytes += sq_stats->tso_inner_bytes;
+ s->tx_added_vlan_packets += sq_stats->added_vlan_packets;
+ s->tx_nop += sq_stats->nop;
+ s->tx_queue_stopped += sq_stats->stopped;
+ s->tx_queue_wake += sq_stats->wake;
+ s->tx_udp_seg_rem += sq_stats->udp_seg_rem;
+ s->tx_queue_dropped += sq_stats->dropped;
+ s->tx_cqe_err += sq_stats->cqe_err;
+ s->tx_recover += sq_stats->recover;
+ s->tx_xmit_more += sq_stats->xmit_more;
+ s->tx_csum_partial_inner += sq_stats->csum_partial_inner;
+ s->tx_csum_none += sq_stats->csum_none;
+ s->tx_csum_partial += sq_stats->csum_partial;
+#ifdef CONFIG_MLX5_EN_TLS
+ s->tx_tls_ooo += sq_stats->tls_ooo;
+ s->tx_tls_resync_bytes += sq_stats->tls_resync_bytes;
+#endif
+ s->tx_cqes += sq_stats->cqes;
+ }
+}
+
void mlx5e_grp_sw_update_stats(struct mlx5e_priv *priv)
{
- struct mlx5e_sw_stats temp, *s = &temp;
+ struct mlx5e_sw_stats s;
int i;

- memset(s, 0, sizeof(*s));
-
- for (i = 0; i < mlx5e_get_netdev_max_channels(priv->netdev); i++) {
- struct mlx5e_channel_stats *channel_stats =
- &priv->channel_stats[i];
- struct mlx5e_xdpsq_stats *xdpsq_red_stats = &channel_stats->xdpsq;
- struct mlx5e_xdpsq_stats *xdpsq_stats = &channel_stats->rq_xdpsq;
- struct mlx5e_rq_stats *rq_stats = &channel_stats->rq;
- struct mlx5e_ch_stats *ch_stats = &channel_stats->ch;
- int j;
-
- s->rx_packets += rq_stats->packets;
- s->rx_bytes += rq_stats->bytes;
- s->rx_lro_packets += rq_stats->lro_packets;
- s->rx_lro_bytes += rq_stats->lro_bytes;
- s->rx_ecn_mark += rq_stats->ecn_mark;
- s->rx_removed_vlan_packets += rq_stats->removed_vlan_packets;
- s->rx_csum_none += rq_stats->csum_none;
- s->rx_csum_complete += rq_stats->csum_complete;
- s->rx_csum_unnecessary += rq_stats->csum_unnecessary;
- s->rx_csum_unnecessary_inner += rq_stats->csum_unnecessary_inner;
- s->rx_xdp_drop += rq_stats->xdp_drop;
- s->rx_xdp_redirect += rq_stats->xdp_redirect;
- s->rx_xdp_tx_xmit += xdpsq_stats->xmit;
- s->rx_xdp_tx_full += xdpsq_stats->full;
- s->rx_xdp_tx_err += xdpsq_stats->err;
- s->rx_xdp_tx_cqe += xdpsq_stats->cqes;
- s->rx_wqe_err += rq_stats->wqe_err;
- s->rx_mpwqe_filler_cqes += rq_stats->mpwqe_filler_cqes;
- s->rx_mpwqe_filler_strides += rq_stats->mpwqe_filler_strides;
- s->rx_buff_alloc_err += rq_stats->buff_alloc_err;
- s->rx_cqe_compress_blks += rq_stats->cqe_compress_blks;
- s->rx_cqe_compress_pkts += rq_stats->cqe_compress_pkts;
- s->rx_page_reuse += rq_stats->page_reuse;
- s->rx_cache_reuse += rq_stats->cache_reuse;
- s->rx_cache_full += rq_stats->cache_full;
- s->rx_cache_empty += rq_stats->cache_empty;
- s->rx_cache_busy += rq_stats->cache_busy;
- s->rx_cache_waive += rq_stats->cache_waive;
- s->rx_congst_umr += rq_stats->congst_umr;
- s->rx_arfs_err += rq_stats->arfs_err;
- s->ch_events += ch_stats->events;
- s->ch_poll += ch_stats->poll;
- s->ch_arm += ch_stats->arm;
- s->ch_aff_change += ch_stats->aff_change;
- s->ch_eq_rearm += ch_stats->eq_rearm;
- /* xdp redirect */
- s->tx_xdp_xmit += xdpsq_red_stats->xmit;
- s->tx_xdp_full += xdpsq_red_stats->full;
- s->tx_xdp_err += xdpsq_red_stats->err;
- s->tx_xdp_cqes += xdpsq_red_stats->cqes;
-
- for (j = 0; j < priv->max_opened_tc; j++) {
- struct mlx5e_sq_stats *sq_stats = &channel_stats->sq[j];
-
- s->tx_packets += sq_stats->packets;
- s->tx_bytes += sq_stats->bytes;
- s->tx_tso_packets += sq_stats->tso_packets;
- s->tx_tso_bytes += sq_stats->tso_bytes;
- s->tx_tso_inner_packets += sq_stats->tso_inner_packets;
- s->tx_tso_inner_bytes += sq_stats->tso_inner_bytes;
- s->tx_added_vlan_packets += sq_stats->added_vlan_packets;
- s->tx_nop += sq_stats->nop;
- s->tx_queue_stopped += sq_stats->stopped;
- s->tx_queue_wake += sq_stats->wake;
- s->tx_udp_seg_rem += sq_stats->udp_seg_rem;
- s->tx_queue_dropped += sq_stats->dropped;
- s->tx_cqe_err += sq_stats->cqe_err;
- s->tx_recover += sq_stats->recover;
- s->tx_xmit_more += sq_stats->xmit_more;
- s->tx_csum_partial_inner += sq_stats->csum_partial_inner;
- s->tx_csum_none += sq_stats->csum_none;
- s->tx_csum_partial += sq_stats->csum_partial;
-#ifdef CONFIG_MLX5_EN_TLS
- s->tx_tls_ooo += sq_stats->tls_ooo;
- s->tx_tls_resync_bytes += sq_stats->tls_resync_bytes;
-#endif
- s->tx_cqes += sq_stats->cqes;
- }
- }
+ memset(&s, 0, sizeof(s));
+
+ for (i = 0; i < mlx5e_get_netdev_max_channels(priv->netdev); i++)
+ mlx5e_grp_sw_collect_stat(priv, &s, i);

- memcpy(&priv->stats.sw, s, sizeof(*s));
+ memcpy(&priv->stats.sw, &s, sizeof(s));
}

static const struct counter_desc q_stats_desc[] = {
--
2.18.0