[PATCH net 1/3] net: ethernet: ti: am65-cpsw-nuss: set irq_disabled after disabling RX IRQ

[Siddharth Vadapalli]

The 'irq_disabled' variable indicates the current state of the RX IRQ and
is used by the RX NAPI handler to determine whether the IRQ should be
enabled.

Currently, 'irq_disabled' is set before actually disabling the IRQ by
invoking disable_irq_nosync(). In an SMP environment, this leads to a race
condition wherein the processor taking the interrupt sets 'irq_disabled'
while another processor executing a previous instance of the RX NAPI
handler sees 'irq_disabled' set and invokes enable_irq() before the RX IRQ
is actually disabled by disable_irq_nosync(). This results in the following
warning:
	Unbalanced enable for IRQ ...

Fix this by disabling the RX IRQ using disable_irq_nosync() before setting
'irq_disabled'.

Fixes: da70d184a8c3 ("net: ethernet: ti: am65-cpsw: Introduce multi queue Rx")
Fixes: 47bfc4d128de ("net: ti: am65-cpsw-nuss: fix RX IRQ state after .ndo_stop()")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 5924db6be3fe..8785ab40f157 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -1570,8 +1570,8 @@ static irqreturn_t am65_cpsw_nuss_rx_irq(int irq, void *dev_id)
 {
 	struct am65_cpsw_rx_flow *flow = dev_id;
 
-	flow->irq_disabled = true;
 	disable_irq_nosync(irq);
+	flow->irq_disabled = true;
 	napi_schedule(&flow->napi_rx);
 
 	return IRQ_HANDLED;
-- 
2.51.1