kernel/linux.git/include/net/netmem.h, branch v6.19.11

net: netmem: remove NET_IOV_MAX from net_iov_type enum

2025-10-29T00:41:46+00:00

Remove the NET_IOV_MAX workaround from the net_iov_type enum. This entry was previously added to force the enum size to unsigned long to satisfy the NET_IOV_ASSERT_OFFSET static assertions. After commit f3d85c9ee510 ("netmem: introduce struct netmem_desc mirroring struct page") this approach became unnecessary by placing the net_iov_type after the netmem_desc. Placing the net_iov_type after netmem_desc results in the net_iov_type size having no effect on the position or layout of the fields that mirror the struct page. The layout before this patch: struct net_iov { union { struct netmem_desc desc; /* 0 48 */ struct { long unsigned int _flags; /* 0 8 */ long unsigned int pp_magic; /* 8 8 */ struct page_pool * pp; /* 16 8 */ long unsigned int _pp_mapping_pad; /* 24 8 */ long unsigned int dma_addr; /* 32 8 */ atomic_long_t pp_ref_count; /* 40 8 */ }; /* 0 48 */ }; /* 0 48 */ struct net_iov_area * owner; /* 48 8 */ enum net_iov_type type; /* 56 8 */ /* size: 64, cachelines: 1, members: 3 */ }; The layout after this patch: struct net_iov { union { struct netmem_desc desc; /* 0 48 */ struct { long unsigned int _flags; /* 0 8 */ long unsigned int pp_magic; /* 8 8 */ struct page_pool * pp; /* 16 8 */ long unsigned int _pp_mapping_pad; /* 24 8 */ long unsigned int dma_addr; /* 32 8 */ atomic_long_t pp_ref_count; /* 40 8 */ }; /* 0 48 */ }; /* 0 48 */ struct net_iov_area * owner; /* 48 8 */ enum net_iov_type type; /* 56 4 */ /* size: 64, cachelines: 1, members: 3 */ /* padding: 4 */ }; Signed-off-by: Bobby Eshleman Reviewed-by: Mina Almasry Link: https://patch.msgid.link/20251024-b4-devmem-remove-niov-max-v1-1-ba72c68bc869@meta.com Signed-off-by: Jakub Kicinski

netmem: replace __netmem_clear_lsb() with netmem_to_nmdesc()

2025-10-14T11:37:26+00:00

Now that we have struct netmem_desc, it'd better access the pp fields via struct netmem_desc rather than struct net_iov. Introduce netmem_to_nmdesc() for safely converting netmem_ref to netmem_desc regardless of the type underneath e.i. netmem_desc, net_iov. While at it, remove __netmem_clear_lsb() and make netmem_to_nmdesc() used instead. Suggested-by: Pavel Begunkov Signed-off-by: Byungchul Park Reviewed-by: Mina Almasry Link: https://patch.msgid.link/20251013044133.69472-1-byungchul@sk.com Signed-off-by: Paolo Abeni

netmem, mlx4: access ->pp_ref_count through netmem_desc instead of page

2025-07-24T00:46:54+00:00

To eliminate the use of struct page in page pool, the page pool users should use netmem descriptor and APIs instead. Make mlx4 access ->pp_ref_count through netmem_desc instead of page. While at it, add a helper, pp_page_to_nmdesc() and __pp_page_to_nmdesc(), that can be used to get netmem_desc from page only if it's a pp page. For now that netmem_desc overlays on page, it can be achieved by just casting, and use macro and _Generic to cover const casting as well. Plus, change page_pool_page_is_pp() to check for 'const struct page *' instead of 'struct page *' since it doesn't modify data and additionally covers const type. Signed-off-by: Byungchul Park Link: https://patch.msgid.link/20250721021835.63939-4-byungchul@sk.com Signed-off-by: Jakub Kicinski

netmem: use netmem_desc instead of page to access ->pp in __netmem_get_pp()

2025-07-24T00:46:54+00:00

To eliminate the use of the page pool fields in struct page, the page pool code should use netmem descriptor and APIs instead. However, __netmem_get_pp() still accesses ->pp via struct page. So change it to use struct netmem_desc instead, since ->pp no longer will be available in struct page. While at it, add a helper, __netmem_to_nmdesc(), that can be used to unsafely get pointer to netmem_desc backing the netmem_ref, only when the netmem_ref is always backed by system memory. Signed-off-by: Byungchul Park Link: https://patch.msgid.link/20250721021835.63939-3-byungchul@sk.com Signed-off-by: Jakub Kicinski

netmem: introduce struct netmem_desc mirroring struct page

2025-07-24T00:46:54+00:00

To simplify struct page, the page pool members of struct page should be moved to other, allowing these members to be removed from struct page. Introduce a network memory descriptor to store the members, struct netmem_desc, and make it union'ed with the existing fields in struct net_iov, allowing to organize the fields of struct net_iov. Signed-off-by: Byungchul Park Reviewed-by: Toke Høiland-Jørgensen Reviewed-by: Pavel Begunkov Reviewed-by: Mina Almasry Reviewed-by: Vlastimil Babka Acked-by: Harry Yoo Link: https://patch.msgid.link/20250721021835.63939-2-byungchul@sk.com Signed-off-by: Jakub Kicinski

netmem: use _Generic to cover const casting for page_to_netmem()

2025-07-08T01:40:10+00:00

The current page_to_netmem() doesn't cover const casting resulting in trying to cast const struct page * to const netmem_ref fails. To cover the case, change page_to_netmem() to use macro and _Generic. Signed-off-by: Byungchul Park Reviewed-by: Mina Almasry Reviewed-by: Toke Høiland-Jørgensen Reviewed-by: Pavel Begunkov Link: https://patch.msgid.link/20250702053256.4594-5-byungchul@sk.com Signed-off-by: Jakub Kicinski

net: Allow const args for of page_to_netmem()

2025-06-18T01:34:11+00:00

This allows calling page_to_netmem() with a const page * argument. Signed-off-by: Dragos Tatulea Reviewed-by: Mina Almasry Reviewed-by: Cosmin Ratiu Signed-off-by: Mark Bloch Link: https://patch.msgid.link/20250616141441.1243044-2-mbloch@nvidia.com Signed-off-by: Jakub Kicinski

netmem: fix netmem comments

2025-06-18T01:00:26+00:00

Trivial fix to a couple of outdated netmem comments. No code changes, just more accurately describing current code. Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250615203511.591438-1-almasrymina@google.com Signed-off-by: Jakub Kicinski

net: enable driver support for netmem TX

2025-05-13T09:12:49+00:00

Drivers need to make sure not to pass netmem dma-addrs to the dma-mapping API in order to support netmem TX. Add helpers and netmem_dma_*() helpers that enables special handling of netmem dma-addrs that drivers can use. Document in netmem.rst what drivers need to do to support netmem TX. Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250508004830.4100853-7-almasrymina@google.com Signed-off-by: Paolo Abeni

net: add get_netmem/put_netmem support

2025-05-13T09:12:48+00:00

Currently net_iovs support only pp ref counts, and do not support a page ref equivalent. This is fine for the RX path as net_iovs are used exclusively with the pp and only pp refcounting is needed there. The TX path however does not use pp ref counts, thus, support for get_page/put_page equivalent is needed for netmem. Support get_netmem/put_netmem. Check the type of the netmem before passing it to page or net_iov specific code to obtain a page ref equivalent. For dmabuf net_iovs, we obtain a ref on the underlying binding. This ensures the entire binding doesn't disappear until all the net_iovs have been put_netmem'ed. We do not need to track the refcount of individual dmabuf net_iovs as we don't allocate/free them from a pool similar to what the buddy allocator does for pages. This code is written to be extensible by other net_iov implementers. get_netmem/put_netmem will check the type of the netmem and route it to the correct helper: pages -> [get|put]_page() dmabuf net_iovs -> net_devmem_[get|put]_net_iov() new net_iovs -> new helpers Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250508004830.4100853-3-almasrymina@google.com Signed-off-by: Paolo Abeni