sfc: don't free_irq()s if they were never requested

If efx_nic_init_interrupt fails, or was never run (e.g. due to an earlier
 failure in ef100_net_open), freeing irqs in efx_nic_fini_interrupt is not
 needed and will cause error messages and stack traces.
So instead, only do this if efx_nic_init_interrupt successfully completed,
 as indicated by the new efx->irqs_hooked flag.

Fixes: 965b549f3c ("sfc_ef100: implement ndo_open/close and EVQ probing")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/net_driver.h

@@ -846,6 +846,7 @@ struct efx_async_filter_insertion {
  * @timer_quantum_ns: Interrupt timer quantum, in nanoseconds
  * @timer_max_ns: Interrupt timer maximum value, in nanoseconds
  * @irq_rx_adaptive: Adaptive IRQ moderation enabled for RX event queues
+ * @irqs_hooked: Channel interrupts are hooked
  * @irq_rx_mod_step_us: Step size for IRQ moderation for RX event queues
  * @irq_rx_moderation_us: IRQ moderation time for RX event queues
  * @msg_enable: Log message enable flags
@@ -1004,6 +1005,7 @@ struct efx_nic {
 	unsigned int timer_quantum_ns;
 	unsigned int timer_max_ns;
 	bool irq_rx_adaptive;
+	bool irqs_hooked;
 	unsigned int irq_mod_step_us;
 	unsigned int irq_rx_moderation_us;
 	u32 msg_enable;

drivers/net/ethernet/sfc/nic.c

@@ -129,6 +129,7 @@ int efx_nic_init_interrupt(struct efx_nic *efx)
 #endif
 	}
 
+	efx->irqs_hooked = true;
 	return 0;
 
  fail2:
@@ -154,6 +155,8 @@ void efx_nic_fini_interrupt(struct efx_nic *efx)
 	efx->net_dev->rx_cpu_rmap = NULL;
 #endif
 
+	if (!efx->irqs_hooked)
+		return;
 	if (EFX_INT_MODE_USE_MSI(efx)) {
 		/* Disable MSI/MSI-X interrupts */
 		efx_for_each_channel(channel, efx)
@@ -163,6 +166,7 @@ void efx_nic_fini_interrupt(struct efx_nic *efx)
 		/* Disable legacy interrupt */
 		free_irq(efx->legacy_irq, efx);
 	}
+	efx->irqs_hooked = false;
 }
 
 /* Register dump */