[PATCH net v3] sfc: fix calling of free_irq with already free vector

[Nikolay Aleksandrov <nikolay@redhat.com>]

If the sfc driver is in legacy interrupt mode (either explicitly by
using interrupt_mode module param or by falling back to it) it will
hit a warning at kernel/irq/manage.c because it will try to free an irq
which wasn't allocated by it in the first place because the MSI(X) irqs are
zero and it'll try to free them unconditionally. So fix it by checking if
we're in legacy mode and freeing the appropriate irqs.

CC: Zenghui Shi <zshi@redhat.com>
CC: Ben Hutchings <ben@decadent.org.uk>
CC: <linux-net-drivers@solarflare.com>
CC: Shradha Shah <sshah@solarflare.com>
CC: David S. Miller <davem@davemloft.net>

Fixes: 1899c111a535 ("sfc: Fix IRQ cleanup in case of a probe failure")
Reported-by: Zenghui Shi <zshi@redhat.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
---
v3: Use the EFX_INT_MODE_USE_MSI macro instead of direct check
as suggested by Ben
v2: Change the fix to check for the interrupt mode and adjust the
commit message.

 drivers/net/ethernet/sfc/nic.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c
index 32d969e857f7..89b83e59e1dc 100644
--- a/drivers/net/ethernet/sfc/nic.c
+++ b/drivers/net/ethernet/sfc/nic.c
@@ -156,13 +156,15 @@ void efx_nic_fini_interrupt(struct efx_nic *efx)
 	efx->net_dev->rx_cpu_rmap = NULL;
 #endif
 
-	/* Disable MSI/MSI-X interrupts */
-	efx_for_each_channel(channel, efx)
-		free_irq(channel->irq, &efx->msi_context[channel->channel]);
-
-	/* Disable legacy interrupt */
-	if (efx->legacy_irq)
+	if (EFX_INT_MODE_USE_MSI(efx)) {
+		/* Disable MSI/MSI-X interrupts */
+		efx_for_each_channel(channel, efx)
+			free_irq(channel->irq,
+				 &efx->msi_context[channel->channel]);
+	} else {
+		/* Disable legacy interrupt */
 		free_irq(efx->legacy_irq, efx);
+	}
 }
 
 /* Register dump */
-- 
1.8.5.3