Re: [net,v2,1/2] net: liquidio: Fix off-by-one error in setup_nic_devices() cleanup

[Simon Horman <horms@kernel.org>]

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---
net: liquidio: Fix off-by-one error in setup_nic_devices() cleanup

This patch changes the cleanup loop from while(i--) to do{}while(i--)
to ensure that when a device fails to initialize, it gets cleaned up
along with all previously initialized devices.

> diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> index 0732440eeacd..3ba2806f5d1e 100644
> --- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
> +++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> @@ -3765,11 +3765,11 @@ static int setup_nic_devices(struct octeon_device *octeon_dev)
>
>  setup_nic_dev_free:
>
> -	while (i--) {
> +	do {
>  		dev_err(&octeon_dev->pci_dev->dev,
>  			"NIC ifidx:%d Setup failed\n", i);
>  		liquidio_destroy_nic_device(octeon_dev, i);
> -	}
> +	} while (i--);

In lio_main.c, setup_nic_devices() can also reach setup_nic_dev_free from
the devlink_alloc() failure path after the main for loop completes. At that
point i equals ifcount (the loop counter has been incremented past the last
valid device).

With the do-while change, the first iteration will call
liquidio_destroy_nic_device(octeon_dev, ifcount) for a device index that
was never initialized. The function has a guard for NULL netdev so it will
not crash, but it will print a spurious error message about a device that
never existed.

The fix works correctly for failures within the loop (which is the case
described in the commit message), but is there a way to handle the
post-loop devlink_alloc() failure case without printing the spurious
error message?

[ ... ]
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pw-bot: cr