sfc: Survive ISR0=0 bug in the shared IRQ case

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/sfc/nic.c b/drivers/net/sfc/nic.c
index db44224ed2ca..8d9696a38edf 100644
--- a/drivers/net/sfc/nic.c
+++ b/drivers/net/sfc/nic.c
@@ -1384,6 +1384,15 @@ static irqreturn_t efx_legacy_interrupt(int irq, void *dev_id)
                 efx->last_irq_cpu = raw_smp_processor_id();
                 EFX_TRACE(efx, "IRQ %d on CPU %d status " EFX_DWORD_FMT "\n",
                           irq, raw_smp_processor_id(), EFX_DWORD_VAL(reg));
+        } else if (EFX_WORKAROUND_15783(efx)) {
+                /* We can't return IRQ_HANDLED more than once on seeing ISR0=0
+                 * because this might be a shared interrupt, but we do need to
+                 * check the channel every time and preemptively rearm it if
+                 * it's idle. */
+                efx_for_each_channel(channel, efx) {
+                        if (!channel->work_pending)
+                                efx_nic_eventq_read_ack(channel);
+                }
         }
 
         return result;