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In order to simplify AF_XDP zero-copy enablement for NIC driver
developers, a new AF_XDP buffer allocation API is added. The
implementation is based on a single core (single producer/consumer)
buffer pool for the AF_XDP UMEM.A buffer is allocated using the xsk_buff_alloc() function, and
returned using xsk_buff_free(). If a buffer is disassociated with the
pool, e.g. when a buffer is passed to an AF_XDP socket, a buffer is
said to be released. Currently, the release function is only used by
the AF_XDP internals and not visible to the driver.Drivers using this API should register the XDP memory model with the
new MEM_TYPE_XSK_BUFF_POOL type.The API is defined in net/xdp_sock_drv.h.
The buffer type is struct xdp_buff, and follows the lifetime of
regular xdp_buffs, i.e. the lifetime of an xdp_buff is restricted to
a NAPI context. In other words, the API is not replacing xdp_frames.In addition to introducing the API and implementations, the AF_XDP
core is migrated to use the new APIs.rfc->v1: Fixed build errors/warnings for m68k and riscv. (kbuild test
robot)
Added headroom/chunk size getter. (Maxim/Björn)v1->v2: Swapped SoBs. (Maxim)
v2->v3: Initialize struct xdp_buff member frame_sz. (Björn)
Add API to query the DMA address of a frame. (Maxim)
Do DMA sync for CPU till the end of the frame to handle
possible growth (frame_sz). (Maxim)Signed-off-by: Björn Töpel
Signed-off-by: Maxim Mikityanskiy
Signed-off-by: Alexei Starovoitov
Link: https://lore.kernel.org/bpf/20200520192103.355233-6-bjorn.topel@gmail.com