drivers: net: cpsw: irq not disabled in cpsw isr in particular sequence

In CPSW NAPI, after processing all interrupts IRQ is enabled and then book
keeping irq_enabled is updated. In random cases when a packet is transmitted
or received between processing packets and IRQ enabled, then just after
enabled IRQ and before irq_enabled is updated, ISR is called so IRQs are
not disabled as irq_enabled is still false and CPU gets locked in CPSW ISR.

By changing the sequence as update the irq_enabled and then enable IRQ
fixes the issue. This issue is not captured always as it is a timing issue
whether Tx or Rx IRQ is invoked between packet processing and enable IRQ.

Cc: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index 59c43918883ecf1f1c3c7693c90c3a3227d4da45..21a5b291b4b39d0ae65dcd8766c9e51a25665dee 100644 (file)
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -555,8 +555,8 @@ static int cpsw_poll(struct napi_struct *napi, int budget)
                cpdma_ctlr_eoi(priv->dma, CPDMA_EOI_RX);
                prim_cpsw = cpsw_get_slave_priv(priv, 0);
                if (prim_cpsw->irq_enabled == false) {
-                       cpsw_enable_irq(priv);
                        prim_cpsw->irq_enabled = true;
+                       cpsw_enable_irq(priv);
                }
        }