kernel/linux.git/include/linux/skbuff_ref.h, branch v6.19.11

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

net: support non paged skb frags

2024-09-12T03:44:31+00:00

Make skb_frag_page() fail in the case where the frag is not backed by a page, and fix its relevant callers to handle this case. Signed-off-by: Mina Almasry Reviewed-by: Eric Dumazet Reviewed-by: Jakub Kicinski Link: https://patch.msgid.link/20240910171458.219195-8-almasrymina@google.com Signed-off-by: Jakub Kicinski

page_pool: convert to use netmem

2024-07-03T01:59:33+00:00

Abstract the memory type from the page_pool so we can later add support for new memory types. Convert the page_pool to use the new netmem type abstraction, rather than use struct page directly. As of this patch the netmem type is a no-op abstraction: it's always a struct page underneath. All the page pool internals are converted to use struct netmem instead of struct page, and the page pool now exports 2 APIs: 1. The existing struct page API. 2. The new struct netmem API. Keeping the existing API is transitional; we do not want to refactor all the current drivers using the page pool at once. The netmem abstraction is currently a no-op. The page_pool uses page_to_netmem() to convert allocated pages to netmem, and uses netmem_to_page() to convert the netmem back to pages to pass to mm APIs, Follow up patches to this series add non-paged netmem support to the page_pool. This change is factored out on its own to limit the code churn to this 1 patch, for ease of code review. Signed-off-by: Mina Almasry Reviewed-by: Pavel Begunkov Link: https://patch.msgid.link/20240628003253.1694510-6-almasrymina@google.com Signed-off-by: Jakub Kicinski

Revert "net: mirror skb frag ref/unref helpers"

2024-05-03T23:05:53+00:00

This reverts commit a580ea994fd37f4105028f5a85c38ff6508a2b25. This revert is to resolve Dragos's report of page_pool leak here: https://lore.kernel.org/lkml/20240424165646.1625690-2-dtatulea@nvidia.com/ The reverted patch interacts very badly with commit 2cc3aeb5eccc ("skbuff: Fix a potential race while recycling page_pool packets"). The reverted commit hopes that the pp_recycle + is_pp_page variables do not change between the skb_frag_ref and skb_frag_unref operation. If such a change occurs, the skb_frag_ref/unref will not operate on the same reference type. In the case of Dragos's report, the grabbed ref was a pp ref, but the unref was a page ref, because the pp_recycle setting on the skb was changed. Attempting to fix this issue on the fly is risky. Lets revert and I hope to reland this with better understanding and testing to ensure we don't regress some edge case while streamlining skb reffing. Fixes: a580ea994fd3 ("net: mirror skb frag ref/unref helpers") Reported-by: Dragos Tatulea Signed-off-by: Mina Almasry Link: https://lore.kernel.org/r/20240502175423.2456544-1-almasrymina@google.com Signed-off-by: Jakub Kicinski

net: mirror skb frag ref/unref helpers

2024-04-12T02:29:23+00:00

Refactor some of the skb frag ref/unref helpers for improved clarity. Implement napi_pp_get_page() to be the mirror counterpart of napi_pp_put_page(). Implement skb_page_ref() to be the mirror of skb_page_unref(). Improve __skb_frag_ref() to become a mirror counterpart of __skb_frag_unref(). Previously unref could handle pp & non-pp pages, while the ref could only handle non-pp pages. Now both the ref & unref helpers can correctly handle both pp & non-pp pages. Now that __skb_frag_ref() can handle both pp & non-pp pages, remove skb_pp_frag_ref(), and use __skb_frag_ref() instead. This lets us remove pp specific handling from skb_try_coalesce. Additionally, since __skb_frag_ref() can now handle both pp & non-pp pages, a latent issue in skb_shift() should now be fixed. Previously this function would do a non-pp ref & pp unref on potential pp frags (fragfrom). After this patch, skb_shift() should correctly do a pp ref/unref on pp frags. Signed-off-by: Mina Almasry Reviewed-by: Dragos Tatulea Reviewed-by: Jacob Keller Link: https://lore.kernel.org/r/20240410190505.1225848-3-almasrymina@google.com Signed-off-by: Jakub Kicinski

net: move skb ref helpers to new header

2024-04-12T02:29:22+00:00

Add a new header, linux/skbuff_ref.h, which contains all the skb_*_ref() helpers. Many of the consumers of skbuff.h do not actually use any of the skb ref helpers, and we can speed up compilation a bit by minimizing this header file. Additionally in the later patch in the series we add page_pool support to skb_frag_ref(), which requires some page_pool dependencies. We can now add these dependencies to skbuff_ref.h instead of a very ubiquitous skbuff.h Signed-off-by: Mina Almasry Link: https://lore.kernel.org/r/20240410190505.1225848-2-almasrymina@google.com Signed-off-by: Jakub Kicinski