[PATCH net 2/3] net: ethernet: ti: icssg_common: set irq_disabled after disabling TX IRQ

[Siddharth Vadapalli]

The 'irq_disabled' variable indicates the current state of the TX IRQ and
is used by the TX 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 TX NAPI
handler sees 'irq_disabled' set and invokes enable_irq() before the TX IRQ
is actually disabled by disable_irq_nosync(). This results in the following
warning:
	Unbalanced enable for IRQ ...

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

Fixes: 8756ef2eb078 ("net: ti: icssg-prueth: Add AF_XDP zero copy for TX")
Cc: <stable at vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli at ti.com>
---
 drivers/net/ethernet/ti/icssg/icssg_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
index 0cf9dfe0fa36..24716c8d7f75 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_common.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
@@ -348,8 +348,8 @@ static irqreturn_t prueth_tx_irq(int irq, void *dev_id)
 {
 	struct prueth_tx_chn *tx_chn = dev_id;
 
-	tx_chn->irq_disabled = true;
 	disable_irq_nosync(irq);
+	tx_chn->irq_disabled = true;
 	napi_schedule(&tx_chn->napi_tx);
 
 	return IRQ_HANDLED;
-- 
2.51.1