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Mina Almasry
72ebc685bc
Clarify the netmem, memory provider, page_pool, and skb fragment design principles in header and code comments: - Memory providers allocate struct net_iov or struct page, cast them to netmem_ref, and pass them to page_pool; page_pool, drivers, and the core stack operate on netmem_ref and must not downcast to page or net_iov outside dedicated netmem helpers. - While current memory providers supply struct net_iov, they are not architecturally restricted to net_iov and may supply page-backed netmems. - While current net_iov types are CPU-unreadable, net_iov has no inherent restrictions and may be readable or unreadable. - New code should generalize existing limitations as much as possible to match these design principles. - Per-provider logic belongs in memory_provider_ops, and per-netmem-type logic belongs in netmem helpers. - All frags in an skb must either all be struct page-backed or all belong to the same memory provider instance; mixing them (including via coalescing) is not allowed. Cc: Luigi Rizzo <lrizzo@google.com> Cc: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Mina Almasry <almasrymina@google.com> Acked-by: Jesper Dangaard Brouer <hawk@kernel.org> Reviewed-by: Björn Töpel <bjorn@kernel.org> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://patch.msgid.link/20261010033630.1171692-2-almasrymina@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>