net: xilinx: axienet: Schedule NAPI in two steps

[ Upstream commit ba0da2d ]

As advised by Documentation/networking/napi.rst, masking IRQs after
calling napi_schedule can be racy. Avoid this by only masking/scheduling
if napi_schedule_prep returns true.

Fixes: 9e2bc26 ("net: axienet: Use NAPI for TX completion path")
Fixes: cc37610 ("net: axienet: implement NAPI and GRO receive")
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20240913145711.2284295-1-sean.anderson@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Sean Anderson

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1042,9 +1042,10 @@ static irqreturn_t axienet_tx_irq(int irq, void *_ndev)
 		u32 cr = lp->tx_dma_cr;
 
 		cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
-		axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
-		napi_schedule(&lp->napi_tx);
+		if (napi_schedule_prep(&lp->napi_tx)) {
+			axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
+			__napi_schedule(&lp->napi_tx);
+		}
 	}
 
 	return IRQ_HANDLED;
@@ -1086,9 +1087,10 @@ static irqreturn_t axienet_rx_irq(int irq, void *_ndev)
 		u32 cr = lp->rx_dma_cr;
 
 		cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
-		axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
-
-		napi_schedule(&lp->napi_rx);
+		if (napi_schedule_prep(&lp->napi_rx)) {
+			axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
+			__napi_schedule(&lp->napi_rx);
+		}
 	}
 
 	return IRQ_HANDLED;