[PATCH net v2] net: stmmac: Clear DMA errors for multi-channel interrupts
From: Maxime Chevallier
Date: Tue Nov 03 2026 - 08:32:16 EST
The Multi-MSI interrupt handler doesn't clear the DMA error interrupts,
and this leads to interrupt storms when one of these interrupts starts
firing :
- The RBU (rx buff unav) which triggers under high traffic load
This triggers easily with iperf3 and small udp packets, and shows
when running the netpoll kselftest
- The RPS (rx process stop) which triggers when we stop the DMA RX.
This one shows when restarting the RX logic without doing a down/up
cycle, like when attaching an XDP program. The XSK kselftests
triggers it.
Let's make sure we clear these interrupts for multi-MSI cases, and call
stmmac_global_err() upon tx_hard_error to avoid possible races with
other interrupts/napi.
For that introduce an "ERR" DMA dir, as we don't want to touch the
RI/TI bits when handling these interrupts.
Both of the above storms have been found on dwmac-motorcomm (YT6801),
and are triggered by the xdp.py, xsk_reconfig.py, xdp_features.py,
ring_reconfig.py and netpoll_basic kernel selftests.
This seems to only affect dwmac4, there's no multi-msi mode on
dwmac1000, and on dwxgmac these interrupts are masked as of today.
Fixes: 6ccf12ae111e ("net: stmmac: use interrupt mode INTM=1 for multi-MSI")
Signed-off-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
---
V2:
- Dropped reviews/tested tags as the implementation has substantially
changed, sorry :(
- Discarded the helper, call directly stmmac_dma_interrupt_status on
all chans and use stmmac_global_err() for TX hard errors, following
sashiko's review.
drivers/net/ethernet/stmicro/stmmac/common.h | 1 +
.../net/ethernet/stmicro/stmmac/dwmac4_dma.h | 5 +++++
.../net/ethernet/stmicro/stmmac/dwmac4_lib.c | 2 ++
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 19 +++++++++++++++++++
4 files changed, 27 insertions(+)
diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index c74bc7c9750e..a972bee66504 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -382,6 +382,7 @@ enum dma_irq_dir {
DMA_DIR_RX = 0x1,
DMA_DIR_TX = 0x2,
DMA_DIR_RXTX = 0x3,
+ DMA_DIR_ERR = 0x4,
};
enum request_irq_err {
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h
index 43b036d4e95b..a7caac3c98e6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.h
@@ -173,6 +173,11 @@ static inline u32 dma_chanx_base_addr(const struct dwmac4_addrs *addrs,
DMA_CHAN_STATUS_TI | \
DMA_CHAN_STATUS_MSK_COMMON)
+#define DMA_CHAN_STATUS_MSK_ERR (DMA_CHAN_STATUS_AIS | \
+ DMA_CHAN_STATUS_FBE | \
+ DMA_CHAN_STATUS_RPS | \
+ DMA_CHAN_STATUS_RBU)
+
int dwmac4_dma_reset(void __iomem *ioaddr);
void dwmac4_enable_dma_irq(struct stmmac_priv *priv, void __iomem *ioaddr,
u32 chan, bool rx, bool tx);
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
index a0249715fafa..02aa1a3dd1e2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
@@ -150,6 +150,8 @@ int dwmac4_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
intr_status &= DMA_CHAN_STATUS_MSK_RX;
else if (dir == DMA_DIR_TX)
intr_status &= DMA_CHAN_STATUS_MSK_TX;
+ else if (dir == DMA_DIR_ERR)
+ intr_status &= DMA_CHAN_STATUS_MSK_ERR;
/* ABNORMAL interrupts */
if (unlikely(intr_status & DMA_CHAN_STATUS_AIS)) {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 7ffed295eb14..6360605ef5ea 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3145,6 +3145,22 @@ static int stmmac_napi_check(struct stmmac_priv *priv, u32 chan, u32 dir)
return status;
}
+static void stmmac_dma_err_interrupt(struct stmmac_priv *priv)
+{
+ u8 channels_to_check = max(priv->plat->rx_queues_to_use,
+ priv->plat->tx_queues_to_use);
+ int status;
+ u8 chan;
+
+ for (chan = 0; chan < channels_to_check; chan++) {
+ status = stmmac_dma_interrupt_status(priv, priv->ioaddr,
+ &priv->xstats, chan,
+ DMA_DIR_ERR);
+ if (unlikely(status & tx_hard_error))
+ stmmac_global_err(priv);
+ }
+}
+
/**
* stmmac_dma_interrupt - DMA ISR
* @priv: driver private structure
@@ -6494,6 +6510,9 @@ static irqreturn_t stmmac_mac_interrupt(int irq, void *dev_id)
/* To handle Common interrupts */
stmmac_common_interrupt(priv);
+ if (priv->plat->core_type == DWMAC_CORE_GMAC4)
+ stmmac_dma_err_interrupt(priv);
+
return IRQ_HANDLED;
}
--
2.56.0