Re: [PATCH net-next v2 07/18] net: Register system page pool as an XDP memory model

Maciej Fijalkowski
2024-10-17T11:32:21Z

On Tue, Oct 15, 2024 at 04:53:39PM +0200, Alexander Lobakin wrote:
> From: Toke Høiland-Jørgensen <toke@redhat.com>
>
> To make the system page pool usable as a source for allocating XDP
> frames, we need to register it with xdp_reg_mem_model(), so that page
> return works correctly. This is done in preparation for using the system
> page pool for the XDP live frame mode in BPF_TEST_RUN; for the same
> reason, make the per-cpu variable non-static so we can access it from
> the test_run code as well.

Again, to me BPF_TEST_RUN has nothing to do with libeth/idpf XDP support
:<

>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> ---
> include/linux/netdevice.h | 1 +
> net/core/dev.c | 10 +++++++++-
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 72f53e7610ec..692f21c28ea5 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3308,6 +3308,7 @@ struct softnet_data {
> };
>
> DECLARE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
> +DECLARE_PER_CPU(struct page_pool *, system_page_pool);
>
> #ifndef CONFIG_PREEMPT_RT
> static inline int dev_recursion_level(void)
> diff --git a/net/core/dev.c b/net/core/dev.c
> index b857abb5c0e9..773388f26d4f 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -460,7 +460,7 @@ EXPORT_PER_CPU_SYMBOL(softnet_data);
> * PP consumers must pay attention to run APIs in the appropriate context
> * (e.g. NAPI context).
> */
> -static DEFINE_PER_CPU(struct page_pool *, system_page_pool);
> +DEFINE_PER_CPU(struct page_pool *, system_page_pool);
>
> #ifdef CONFIG_LOCKDEP
> /*
> @@ -12103,11 +12103,18 @@ static int net_page_pool_create(int cpuid)
> .nid = cpu_to_mem(cpuid),
> };
> struct page_pool *pp_ptr;
> + int err;
>
> pp_ptr = page_pool_create_percpu(&page_pool_params, cpuid);
> if (IS_ERR(pp_ptr))
> return -ENOMEM;
>
> + err = xdp_reg_page_pool(pp_ptr);
> + if (err) {
> + page_pool_destroy(pp_ptr);
> + return err;
> + }
> +
> per_cpu(system_page_pool, cpuid) = pp_ptr;
> #endif
> return 0;
> @@ -12241,6 +12248,7 @@ static int __init net_dev_init(void)
> if (!pp_ptr)
> continue;
>
> + xdp_unreg_page_pool(pp_ptr);
> page_pool_destroy(pp_ptr);
> per_cpu(system_page_pool, i) = NULL;
> }
> --
> 2.46.2
>