Commit eb91e4d4 authored Aug 10, 2018 by Björn Töpel Committed by Daniel Borkmann Aug 10, 2018

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



This reverts commit 36e0f12b.

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>

parent a736e074

net/core/xdp.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -348,7 +348,6 @@ 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);
		rcu_read_unlock();
		default:

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