Re: [Intel-wired-lan] [e1000-patches] [PATCH net-next v1] ixgbe: XDP: fix checker warning from rcu pointer

Re: [Intel-wired-lan] [e1000-patches] [PATCH net-next v1] ixgbe: XDP: fix checker warning from rcu pointer

[Rout, ChandanX]

-----Original Message-----
From: e1000-patches-request@eclists.intel.com <e1000-patches-request@eclists.intel.com> On Behalf Of Fijalkowski, Maciej
Sent: 15 November 2022 18:39
To: Brandeburg, Jesse <jesse.brandeburg@intel.com>
Cc: e1000-patches@eclists.intel.com
Subject: Re: [e1000-patches] [PATCH net-next v1] ixgbe: XDP: fix checker warning from rcu pointer

On Mon, Nov 14, 2022 at 03:16:23PM -0800, Jesse Brandeburg wrote:
> The ixgbe driver uses an older style failure mode when initializing 
> the XDP program and the queues. It causes some warnings when running 
> C=2 checking builds (and it's the last one in the ethernet/intel tree).
> 
> $ make W=1 C=2 M=drivers/net/ethernet/intel modules
> .../ixgbe_main.c:10301:25: error: incompatible types in comparison expression (different address spaces):
> .../ixgbe_main.c:10301:25:    struct bpf_prog [noderef] __rcu *
> .../ixgbe_main.c:10301:25:    struct bpf_prog *
> 
> Fix the problem by removing the line that tried to restore "the old 
> prog pointer" if there was an error, to make this driver act like the 
> other drivers which return the error code without "pointer restoration."

I think we could just remove the pointer restoration as there is a high chance that driver will misbehave if setting up resources failed. It won't work correctly with old prog.

> 
> Also, update the "copy the pointer" logic to use WRITE_ONCE as 
> many/all the other drivers do.
> 
> The code here was modeled after the code in i40e/i40e_xdp_setup().
> 
> NOTE: Compile-tested only.
> 
> CC: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
_______________________________________________
Intel-wired-lan mailing list
Intel-wired-lan@osuosl.org
https://lists.osuosl.org/mailman/listinfo/intel-wired-lan