From: John Fastabend <john.fastabend@xxxxxxxxx>
Date: Wed, 03 Apr 2024 13:20:32 -0700
> Toke Høiland-Jørgensen wrote:
>> 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.
>>
>> Reviewed-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
>> Tested-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>> ---
>> include/linux/netdevice.h | 1 +
>> net/core/dev.c | 13 ++++++++++++-
>> 2 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index c541550b0e6e..e1dfdf0c4075 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -3345,6 +3345,7 @@ static inline void input_queue_tail_incr_save(struct softnet_data *sd,
>> }
>>
>> DECLARE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
>> +DECLARE_PER_CPU_ALIGNED(struct page_pool *, system_page_pool);
>>
>> static inline int dev_recursion_level(void)
>> {
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index d8dd293a7a27..cdb916a647e7 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -428,7 +428,7 @@ 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_ALIGNED(struct page_pool *, system_page_pool);
>> +DEFINE_PER_CPU_ALIGNED(struct page_pool *, system_page_pool);
>>
>> #ifdef CONFIG_LOCKDEP
>> /*
>> @@ -11739,12 +11739,20 @@ static int net_page_pool_create(int cpuid)
>> .pool_size = SYSTEM_PERCPU_PAGE_POOL_SIZE,
>> .nid = NUMA_NO_NODE,
>> };
>> + struct xdp_mem_info info;
>> 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_mem_model(&info, MEM_TYPE_PAGE_POOL, pp_ptr);
>> + if (err) {
>> + page_pool_destroy(pp_ptr);
>> + return err;
>> + }
>> +
>> per_cpu(system_page_pool, cpuid) = pp_ptr;
>> #endif
>> return 0;
>> @@ -11834,12 +11842,15 @@ static int __init net_dev_init(void)
>> out:
>> if (rc < 0) {
>> for_each_possible_cpu(i) {
>> + struct xdp_mem_info mem = { .type = MEM_TYPE_PAGE_POOL };
>> struct page_pool *pp_ptr;
>>
>> pp_ptr = per_cpu(system_page_pool, i);
>> if (!pp_ptr)
>> continue;
>>
>> + mem.id = pp_ptr->xdp_mem_id;
>> + xdp_unreg_mem_model(&mem);
>
> Take it or leave it, a net_page_pool_destroy(int cpuid) would be
> symmetric here.
>
>> page_pool_destroy(pp_ptr);
I believe it's better to remove this page_pool_destroy() and let
xdp_unreg_mem_model() destroy it.
>> per_cpu(system_page_pool, i) = NULL;
>> }
>
> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Thanks,
Olek
