[PATCH net] igc: Fix infinite initialization loop with early XDP redirect

[PATCH net] igc: Fix infinite initialization loop with early XDP redirect

[Tony Nguyen]

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>

When an XDP redirect happens before the link is ready, that
transmission will not finish and will timeout, causing an adapter
reset. If the redirects do not stop, the adapter will not stop
resetting.

Wait for the driver to signal that there's a carrier before allowing
transmissions to proceed.

Previous code was relying that when __IGC_DOWN is cleared, the NIC is
ready to transmit as all the queues are ready, what happens is that
the carrier presence will only be signaled later, after the watchdog
workqueue has a chance to run. And during this interval (between
clearing __IGC_DOWN and the watchdog running) if any transmission
happens the timeout is emitted (detected by igc_tx_timeout()) which
causes the reset, with the potential for the infinite loop.

Fixes: 4ff320361092 ("igc: Add support for XDP_REDIRECT action")
Reported-by: Ferenc Fejes <ferenc.fejes@ericsson.com>
Closes: https://lore.kernel.org/netdev/0caf33cf6adb3a5bf137eeaa20e89b167c9986d5.camel@ericsson.com/
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Ferenc Fejes <ferenc.fejes@ericsson.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 293b45717683..98de34d0ce07 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6491,7 +6491,7 @@ static int igc_xdp_xmit(struct net_device *dev, int num_frames,
 	struct igc_ring *ring;
 	int i, drops;
 
-	if (unlikely(test_bit(__IGC_DOWN, &adapter->state)))
+	if (unlikely(!netif_carrier_ok(dev)))
 		return -ENETDOWN;
 
 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
-- 
2.38.1

Re: [PATCH net] igc: Fix infinite initialization loop with early XDP redirect

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Wed, 13 Sep 2023 11:06:15 -0700 you wrote:
> From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
> 
> When an XDP redirect happens before the link is ready, that
> transmission will not finish and will timeout, causing an adapter
> reset. If the redirects do not stop, the adapter will not stop
> resetting.
> 
> [...]

Here is the summary with links:
  - [net] igc: Fix infinite initialization loop with early XDP redirect
    https://git.kernel.org/netdev/net/c/cb47b1f679c4

You are awesome, thank you!
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