[PATCH 5.4 43/67] igb: reinit_locked() should be called with rtnl_lock

Greg Kroah-Hartman
2020-08-10T15:27:57Z

From: Francesco Ruggeri <fruggeri@arista.com>

[ Upstream commit 024a8168b749db7a4aa40a5fbdfa04bf7e77c1c0 ]

We observed two panics involving races with igb_reset_task.
The first panic is caused by this race condition:

kworker reboot -f

igb_reset_task
igb_reinit_locked
igb_down
napi_synchronize
__igb_shutdown
igb_clear_interrupt_scheme
igb_free_q_vectors
igb_free_q_vector
adapter->q_vector[v_idx] = NULL;
napi_disable
Panics trying to access
adapter->q_vector[v_idx].napi_state

The second panic (a divide error) is caused by this race:

kworker reboot -f tx packet

igb_reset_task
__igb_shutdown
rtnl_lock()
...
igb_clear_interrupt_scheme
igb_free_q_vectors
adapter->num_tx_queues = 0
...
rtnl_unlock()
rtnl_lock()
igb_reinit_locked
igb_down
igb_up
netif_tx_start_all_queues
dev_hard_start_xmit
igb_xmit_frame
igb_tx_queue_mapping
Panics on
r_idx % adapter->num_tx_queues

This commit applies to igb_reset_task the same changes that
were applied to ixgbe in commit 2f90b8657ec9 ("ixgbe: this patch
adds support for DCB to the kernel and ixgbe driver"),
commit 8f4c5c9fb87a ("ixgbe: reinit_locked() should be called with
rtnl_lock") and commit 88adce4ea8f9 ("ixgbe: fix possible race in
reset subtask").

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/igb/igb_main.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index ed7e667d7eb29..3e41b20ed8eb5 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6194,9 +6194,18 @@ static void igb_reset_task(struct work_struct *work)
struct igb_adapter *adapter;
adapter = container_of(work, struct igb_adapter, reset_task);

+ rtnl_lock();
+ /* If we're already down or resetting, just bail */
+ if (test_bit(__IGB_DOWN, &adapter->state) ||
+ test_bit(__IGB_RESETTING, &adapter->state)) {
+ rtnl_unlock();
+ return;
+ }
+
igb_dump(adapter);
netdev_err(adapter->netdev, "Reset adapter\n");
igb_reinit_locked(adapter);
+ rtnl_unlock();
}

/**
--
2.25.1