2018-07-21 2:18 GMT+09:00 Martin KaFai Lau <ka...@fb.com>:
> On Sat, Jul 21, 2018 at 01:04:45AM +0900, Taehee Yoo wrote:
>> rhashtable_lookup() can return NULL. so that NULL pointer
>> check routine should be added.
>>
>> Fixes: 02b55e5657c3 ("xdp: add MEM_TYPE_ZERO_COPY")
>> Signed-off-by: Taehee Yoo <ap420...@gmail.com>
>> ---
>> net/core/xdp.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/core/xdp.c b/net/core/xdp.c
>> index 9d1f220..1c12bc7 100644
>> --- a/net/core/xdp.c
>> +++ b/net/core/xdp.c
>> @@ -345,7 +345,8 @@ static void __xdp_return(void *data, struct xdp_mem_info
>> *mem, bool napi_direct,
>> rcu_read_lock();
>> /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
>> xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
>> - xa->zc_alloc->free(xa->zc_alloc, handle);
>> + if (xa)
>> + xa->zc_alloc->free(xa->zc_alloc, handle);
> hmm...It is not clear to me the "!xa" case don't have to be handled?
Thank you for reviewing!
Returning NULL pointer is bug case such as calling after use
xdp_rxq_info_unreg().
so that, I think it can't handle at that moment.
we can make __xdp_return to add WARN_ON_ONCE() or
add return error code to driver.
But I'm not sure if these is useful information.
I might have misunderstood scenario of MEM_TYPE_ZERO_COPY
because there is no use case of MEM_TYPE_ZERO_COPY yet.
Thanks!
>
>> rcu_read_unlock();
>> default:
>> /* Not possible, checked in xdp_rxq_info_reg_mem_model() */
>> --
>> 2.9.3
>>
