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Revert "xdp: add NULL pointer check in __xdp_return()" 

This reverts commit 36e0f12bbf.

The reverted commit adds a WARN to check against NULL entries in the
mem_id_ht rhashtable. Any kernel path implementing the XDP (generic or
driver) fast path is required to make a paired
xdp_rxq_info_reg/xdp_rxq_info_unreg call for proper function. In
addition, a driver using a different allocation scheme than the
default MEM_TYPE_PAGE_SHARED is required to additionally call
xdp_rxq_info_reg_mem_model.

For MEM_TYPE_ZERO_COPY, an xdp_rxq_info_reg_mem_model call ensures
that the mem_id_ht rhashtable has a properly inserted allocator id. If
not, this would be a driver bug. A NULL pointer kernel OOPS is
preferred to the WARN.

Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Björn Töpel 2018-08-10 11:28:02 +02:00 committed by Daniel Borkmann
parent a736e07468
commit eb91e4d4db
1 changed files with 1 additions and 2 deletions
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3
net/core/xdp.c
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@ -348,8 +348,7 @@ 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);
if (!WARN_ON_ONCE(!xa))
xa->zc_alloc->free(xa->zc_alloc, handle);
xa->zc_alloc->free(xa->zc_alloc, handle);
rcu_read_unlock();
default:
/* Not possible, checked in xdp_rxq_info_reg_mem_model() */