[PATCH] net: stmmac: protect statistics updates with a spinlock
From: Petr Tesarik
Date: Fri Jan 05 2024 - 04:16:49 EST
Add a spinlock to fix race conditions while updating Tx/Rx statistics.
As explained by a comment in <linux/u64_stats_sync.h>, write side of struct
u64_stats_sync must ensure mutual exclusion, or one seqcount update could
be lost on 32-bit platforms, thus blocking readers forever.
Such lockups have been actually observed on 32-bit Arm after stmmac_xmit()
on one core raced with stmmac_napi_poll_tx() on another core.
Signed-off-by: Petr Tesarik <petr@xxxxxxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/common.h | 2 +
.../net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 4 +
.../net/ethernet/stmicro/stmmac/dwmac4_lib.c | 4 +
.../net/ethernet/stmicro/stmmac/dwmac_lib.c | 4 +
.../ethernet/stmicro/stmmac/dwxgmac2_dma.c | 4 +
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 80 +++++++++++++------
6 files changed, 72 insertions(+), 26 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index e3f650e88f82..9a17dfc1055d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -70,6 +70,7 @@ struct stmmac_txq_stats {
u64 tx_tso_frames;
u64 tx_tso_nfrags;
struct u64_stats_sync syncp;
+ spinlock_t lock; /* mutual writer exclusion */
} ____cacheline_aligned_in_smp;
struct stmmac_rxq_stats {
@@ -79,6 +80,7 @@ struct stmmac_rxq_stats {
u64 rx_normal_irq_n;
u64 napi_poll;
struct u64_stats_sync syncp;
+ spinlock_t lock; /* mutual writer exclusion */
} ____cacheline_aligned_in_smp;
/* Extra statistic and debug information exposed by ethtool */
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index 137741b94122..9c568996321d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -455,9 +455,11 @@ static int sun8i_dwmac_dma_interrupt(struct stmmac_priv *priv,
if (v & EMAC_TX_INT) {
ret |= handle_tx;
+ spin_lock(&txq_stats->lock);
u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_normal_irq_n++;
u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock(&txq_stats->lock);
}
if (v & EMAC_TX_DMA_STOP_INT)
@@ -479,9 +481,11 @@ static int sun8i_dwmac_dma_interrupt(struct stmmac_priv *priv,
if (v & EMAC_RX_INT) {
ret |= handle_rx;
+ spin_lock(&rxq_stats->lock);
u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_normal_irq_n++;
u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock(&rxq_stats->lock);
}
if (v & EMAC_RX_BUF_UA_INT)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
index 9470d3fd2ded..e50e8b07724b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
@@ -201,15 +201,19 @@ int dwmac4_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
}
/* TX/RX NORMAL interrupts */
if (likely(intr_status & DMA_CHAN_STATUS_RI)) {
+ spin_lock(&rxq_stats->lock);
u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_normal_irq_n++;
u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock(&rxq_stats->lock);
ret |= handle_rx;
}
if (likely(intr_status & DMA_CHAN_STATUS_TI)) {
+ spin_lock(&txq_stats->lock);
u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_normal_irq_n++;
u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock(&txq_stats->lock);
ret |= handle_tx;
}
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
index 7907d62d3437..a43396a7f852 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
@@ -215,16 +215,20 @@ int dwmac_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
u32 value = readl(ioaddr + DMA_INTR_ENA);
/* to schedule NAPI on real RIE event. */
if (likely(value & DMA_INTR_ENA_RIE)) {
+ spin_lock(&rxq_stats->lock);
u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_normal_irq_n++;
u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock(&rxq_stats->lock);
ret |= handle_rx;
}
}
if (likely(intr_status & DMA_STATUS_TI)) {
+ spin_lock(&txq_stats->lock);
u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_normal_irq_n++;
u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock(&txq_stats->lock);
ret |= handle_tx;
}
if (unlikely(intr_status & DMA_STATUS_ERI))
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
index 3cde695fec91..f4e01436d4cc 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
@@ -367,15 +367,19 @@ static int dwxgmac2_dma_interrupt(struct stmmac_priv *priv,
/* TX/RX NORMAL interrupts */
if (likely(intr_status & XGMAC_NIS)) {
if (likely(intr_status & XGMAC_RI)) {
+ spin_lock(&rxq_stats->lock);
u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_normal_irq_n++;
u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock(&rxq_stats->lock);
ret |= handle_rx;
}
if (likely(intr_status & (XGMAC_TI | XGMAC_TBU))) {
+ spin_lock(&txq_stats->lock);
u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_normal_irq_n++;
u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock(&txq_stats->lock);
ret |= handle_tx;
}
}
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 37e64283f910..82d8db04d0d1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2515,9 +2515,11 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
entry = tx_q->cur_tx;
}
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_set_ic_bit += tx_set_ic_bit;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
if (tx_desc) {
stmmac_flush_tx_descriptors(priv, queue);
@@ -2721,11 +2723,13 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue,
if (tx_q->dirty_tx != tx_q->cur_tx)
*pending_packets = true;
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_packets += tx_packets;
txq_stats->tx_pkt_n += tx_packets;
txq_stats->tx_clean++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
priv->xstats.tx_errors += tx_errors;
@@ -4311,13 +4315,15 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
netif_tx_stop_queue(netdev_get_tx_queue(priv->dev, queue));
}
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_bytes += skb->len;
txq_stats->tx_tso_frames++;
txq_stats->tx_tso_nfrags += nfrags;
if (set_ic)
txq_stats->tx_set_ic_bit++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
if (priv->sarc_type)
stmmac_set_desc_sarc(priv, first, priv->sarc_type);
@@ -4560,11 +4566,13 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
netif_tx_stop_queue(netdev_get_tx_queue(priv->dev, queue));
}
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_bytes += skb->len;
if (set_ic)
txq_stats->tx_set_ic_bit++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
if (priv->sarc_type)
stmmac_set_desc_sarc(priv, first, priv->sarc_type);
@@ -4831,9 +4839,11 @@ static int stmmac_xdp_xmit_xdpf(struct stmmac_priv *priv, int queue,
unsigned long flags;
tx_q->tx_count_frames = 0;
stmmac_set_tx_ic(priv, tx_desc);
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->tx_set_ic_bit++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
}
stmmac_enable_dma_transmission(priv, priv->ioaddr);
@@ -5008,10 +5018,12 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
skb_record_rx_queue(skb, queue);
napi_gro_receive(&ch->rxtx_napi, skb);
- flags = u64_stats_update_begin_irqsave(&rxq_stats->syncp);
+ spin_lock_irqsave(&rxq_stats->lock, flags);
+ u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_pkt_n++;
rxq_stats->rx_bytes += len;
- u64_stats_update_end_irqrestore(&rxq_stats->syncp, flags);
+ u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock_irqrestore(&rxq_stats->lock, flags);
}
static bool stmmac_rx_refill_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
@@ -5248,9 +5260,11 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue)
stmmac_finalize_xdp_rx(priv, xdp_status);
- flags = u64_stats_update_begin_irqsave(&rxq_stats->syncp);
+ spin_lock_irqsave(&rxq_stats->lock, flags);
+ u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_pkt_n += count;
- u64_stats_update_end_irqrestore(&rxq_stats->syncp, flags);
+ u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock_irqrestore(&rxq_stats->lock, flags);
priv->xstats.rx_dropped += rx_dropped;
priv->xstats.rx_errors += rx_errors;
@@ -5541,11 +5555,13 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
stmmac_rx_refill(priv, queue);
- flags = u64_stats_update_begin_irqsave(&rxq_stats->syncp);
+ spin_lock_irqsave(&rxq_stats->lock, flags);
+ u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->rx_packets += rx_packets;
rxq_stats->rx_bytes += rx_bytes;
rxq_stats->rx_pkt_n += count;
- u64_stats_update_end_irqrestore(&rxq_stats->syncp, flags);
+ u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock_irqrestore(&rxq_stats->lock, flags);
priv->xstats.rx_dropped += rx_dropped;
priv->xstats.rx_errors += rx_errors;
@@ -5564,9 +5580,11 @@ static int stmmac_napi_poll_rx(struct napi_struct *napi, int budget)
int work_done;
rxq_stats = &priv->xstats.rxq_stats[chan];
- flags = u64_stats_update_begin_irqsave(&rxq_stats->syncp);
+ spin_lock_irqsave(&rxq_stats->lock, flags);
+ u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->napi_poll++;
- u64_stats_update_end_irqrestore(&rxq_stats->syncp, flags);
+ u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock_irqrestore(&rxq_stats->lock, flags);
work_done = stmmac_rx(priv, budget, chan);
if (work_done < budget && napi_complete_done(napi, work_done)) {
@@ -5592,9 +5610,11 @@ static int stmmac_napi_poll_tx(struct napi_struct *napi, int budget)
int work_done;
txq_stats = &priv->xstats.txq_stats[chan];
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock_irqsave(&txq_stats->lock, flags);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->napi_poll++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
work_done = stmmac_tx_clean(priv, budget, chan, &pending_packets);
work_done = min(work_done, budget);
@@ -5627,14 +5647,18 @@ static int stmmac_napi_poll_rxtx(struct napi_struct *napi, int budget)
unsigned long flags;
rxq_stats = &priv->xstats.rxq_stats[chan];
- flags = u64_stats_update_begin_irqsave(&rxq_stats->syncp);
+ spin_lock_irqsave(&rxq_stats->lock, flags);
+ u64_stats_update_begin(&rxq_stats->syncp);
rxq_stats->napi_poll++;
- u64_stats_update_end_irqrestore(&rxq_stats->syncp, flags);
+ u64_stats_update_end(&rxq_stats->syncp);
+ spin_unlock(&rxq_stats->lock);
txq_stats = &priv->xstats.txq_stats[chan];
- flags = u64_stats_update_begin_irqsave(&txq_stats->syncp);
+ spin_lock(&txq_stats->lock);
+ u64_stats_update_begin(&txq_stats->syncp);
txq_stats->napi_poll++;
- u64_stats_update_end_irqrestore(&txq_stats->syncp, flags);
+ u64_stats_update_end(&txq_stats->syncp);
+ spin_unlock_irqrestore(&txq_stats->lock, flags);
tx_done = stmmac_tx_clean(priv, budget, chan, &tx_pending_packets);
tx_done = min(tx_done, budget);
@@ -7371,10 +7395,14 @@ int stmmac_dvr_probe(struct device *device,
priv->device = device;
priv->dev = ndev;
- for (i = 0; i < MTL_MAX_RX_QUEUES; i++)
+ for (i = 0; i < MTL_MAX_RX_QUEUES; i++) {
u64_stats_init(&priv->xstats.rxq_stats[i].syncp);
- for (i = 0; i < MTL_MAX_TX_QUEUES; i++)
+ spin_lock_init(&priv->xstats.rxq_stats[i].lock);
+ }
+ for (i = 0; i < MTL_MAX_TX_QUEUES; i++) {
u64_stats_init(&priv->xstats.txq_stats[i].syncp);
+ spin_lock_init(&priv->xstats.txq_stats[i].lock);
+ }
stmmac_set_ethtool_ops(ndev);
priv->pause = pause;
--
2.43.0