9bb984f28d
This patch is to simplify the uapi bpf.h regarding to the tstamp type and use a similar way as the kernel to describe the value stored in __sk_buff->tstamp. My earlier thought was to avoid describing the semantic and clock base for the rcv timestamp until there is more clarity on the use case, so the __sk_buff->delivery_time_type naming instead of __sk_buff->tstamp_type. With some thoughts, it can reuse the UNSPEC naming. This patch first removes BPF_SKB_DELIVERY_TIME_NONE and also rename BPF_SKB_DELIVERY_TIME_UNSPEC to BPF_SKB_TSTAMP_UNSPEC and BPF_SKB_DELIVERY_TIME_MONO to BPF_SKB_TSTAMP_DELIVERY_MONO. The semantic of BPF_SKB_TSTAMP_DELIVERY_MONO is the same: __sk_buff->tstamp has delivery time in mono clock base. BPF_SKB_TSTAMP_UNSPEC means __sk_buff->tstamp has the (rcv) tstamp at ingress and the delivery time at egress. At egress, the clock base could be found from skb->sk->sk_clockid. __sk_buff->tstamp == 0 naturally means NONE, so NONE is not needed. With BPF_SKB_TSTAMP_UNSPEC for the rcv tstamp at ingress, the __sk_buff->delivery_time_type is also renamed to __sk_buff->tstamp_type which was also suggested in the earlier discussion: https://lore.kernel.org/bpf/b181acbe-caf8-502d-4b7b-7d96b9fc5d55@iogearbox.net/ The above will then make __sk_buff->tstamp and __sk_buff->tstamp_type the same as its kernel skb->tstamp and skb->mono_delivery_time counter part. The internal kernel function bpf_skb_convert_dtime_type_read() is then renamed to bpf_skb_convert_tstamp_type_read() and it can be simplified with the BPF_SKB_DELIVERY_TIME_NONE gone. A BPF_ALU32_IMM(BPF_AND) insn is also saved by using BPF_JMP32_IMM(BPF_JSET). The bpf helper bpf_skb_set_delivery_time() is also renamed to bpf_skb_set_tstamp(). The arg name is changed from dtime to tstamp also. It only allows setting tstamp 0 for BPF_SKB_TSTAMP_UNSPEC and it could be relaxed later if there is use case to change mono delivery time to non mono. prog->delivery_time_access is also renamed to prog->tstamp_type_access. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220309090509.3712315-1-kafai@fb.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.