[PATCH v2] api: packet: redefine packet data sharing #2287
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odpbuild
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ashwinyes
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Nov 20, 2025
| * Packets returned by this function can be used normally in ODP API functions | ||
| * unless otherwise noted. There are restrictions in packet output. | ||
| * | ||
| * Referenced packets can be used in ODP API functions that treat packet data |
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I think we should use one word to refer. Either base packet or referenced packet.
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Changed in v2 so that we talk about referenced packets, not base packets.
ashwinyes
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Nov 20, 2025
include/odp/api/spec/packet.h
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| * of a static reference it also shares metadata. Packet data and data layout | ||
| * of packet that have references must be treated as read only. | ||
| * | ||
| * Packets created through odp_packet_ref() or odp_packet_ref_hdr() share data |
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odp_packet_ref_hdr() --> odp_packet_ref_pkt()
Current API regarding dynamic packet references is not easy to efficiently support in some ODP implementations with HW accelerated packet output due to the need to update reference counts after TX completion and based on that conditionally free packet buffers. odp_packet_ref() has been implemented only as a full packet copy in all ODP implementation. Redefine the semantics of odp_packet_ref() and the packets involved in packet data sharing in a way that hopefully makes it simpler to support packet data sharing with restrictions in packet output and with per-packet reference counting instead of per-segment reference counting. The new semantics also enable use cases that were not previously possible. Specify better the rules regarding packet data layout manipulation operations, allowing private packet data also in the tail of the packets that reference other packets. Pull and truncate operations may involve shared packet data, in which case they just remove that data from the packet, not affecting the packet owning the data. All extend and truncate operations always produce non-shared packet data. Change odp_packet_has_ref() to indicate whether a packet is referenced by another packet, not whether the packet shares data with another packet. In partivular, odp_packet_ref() returns a packet that shares data with the given packet but is not itself referenced by other packets. Specify that packet data and layout of packets referenced by other packets can not be modified at all. Add new odp_packet_is_referencing() to test whether a packet references another packet. Introduce pktio capability bits to indicate whether a pktio supports sending packets with shared data without using the dont_free flag. Sending with the dont_free flag is supported with all types of packets. Signed-off-by: Janne Peltonen <janne.peltonen@nokia.com>
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odpbuild
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v2: Many text clarifications and typo fixes. Removed base packet from terminology. Made the packet I/O capabilities more granular. Added reference related text in odp_packet_concat() specification. Added a new function to test whether a packet is a referencing packet. Mentioned that the functions that create referencing packets and static references can be called simultaneously in multiple threads for the same packet. |
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Current API regarding dynamic packet references is not easy to efficiently support in some ODP implementations with HW accelerated packet output due to the need to update reference counts after TX completion and based on that conditionally free packet buffers. odp_packet_ref() has been implemented only as a full packet copy in all ODP implementation.
Redefine the semantics of odp_packet_ref() and the packets involved in packet data sharing in a way that hopefully makes it simpler to support packet data sharing with restrictions in packet output and with per-packet reference counting instead of per-segment reference counting. The new semantics also enable use cases that were not previously possible.
Specify better the rules regarding packet data layout manipulation operations, allowing private packet data also in the tail of the packets that reference other packets. Pull and truncate operations may involve shared packet data, in which case they just remove that data from the packet, not affecting the packet owning the data. All extend and truncate operations always produce non-shared packet data.
Change odp_packet_has_ref() to indicate whether a packet is referenced by another packet, not whether the packet shares data with another packet. In partivular, odp_packet_ref() returns a packet that shares data with the given packet but is not itself referenced by other packets. Specify that packet data and layout of packets referenced by other packets can not be modified at all.
Introduce pktio capability bits to indicate whether a pktio supports sending packets with shared data without using the dont_free flag. Sending with the dont_free flag is supported with all types of packets.