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From: Alexei Starovoitov <ast@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	john fastabend <john.fastabend@gmail.com>,
	bpf <bpf@vger.kernel.org>, Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v4 bpf-next 15/22] libbpf: Use fd_array only with gen_loader.
Date: Tue, 11 May 2021 21:17:41 -0700	[thread overview]
Message-ID: <8122c5c0-1429-9f2d-c73a-9d8ada4f318e@fb.com> (raw)
In-Reply-To: <CAEf4BzaBS4hhiSvsLcdZvSQv598+ODAyXstLcFgEhzEmzmj2yw@mail.gmail.com>

On 5/11/21 4:24 PM, Andrii Nakryiko wrote:
> On Fri, May 7, 2021 at 8:49 PM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
>>
>> From: Alexei Starovoitov <ast@kernel.org>
>>
>> Rely on fd_array kernel feature only to generate loader program,
>> since it's mandatory for it.
>> Avoid using fd_array by default to preserve test coverage
>> for old style map_fd patching.
>>
>> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>> ---
> 
> As mentioned in the previous patch, this is almost a complete undo of
> one of the earlier patches, but it also leaves FEAT_FD_IDX and
> probe_kern_fd_idx() around. Can you please try to combine them?

I cannot combine 9 and this 15, because then 14 will be broken.
I'd have to combine all 3, but then the fd_idx won't get its own
test coverage.
With patches 1 through 9 I've tested the whole test_progs
and that gives the confidence that kernel and libbpf side
are doing it correctly.
Then with the rest of patches and without 15 I test everything again.
Such testing approach covers lskel and fd_idx together.
I think this patch 15 is rather unnecessary. It's here only because
you didn't like patch 9.
I think patch 9 is a good default for libbpf to take.
Eventually llvm can emit .o with fd_idx style.
The libbpf would just call probe_kern_fd_idx() and won't need
to massage the .text after llvm if kernel supports it.
It would need to sanitize back to BPF_PSEUDO_MAP_FD only on older kernels.
That's the reason I'm not deleting probe_kern_fd_idx() in this patch,
because I think it will be used fairly soon.
But I can delete it too if you insist.
But combining 9,14,15 into one I'd like to avoid.
I think there is a value to have this in git to easily go back later
to test everything in fd_idx mode by reverting this patch 15.

  reply	other threads:[~2021-05-12  4:18 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-08  3:48 [PATCH v4 bpf-next 00/22] bpf: syscall program, FD array, loader program, light skeleton Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 01/22] bpf: Introduce bpf_sys_bpf() helper and program type Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 02/22] bpf: Introduce bpfptr_t user/kernel pointer Alexei Starovoitov
2021-05-11 22:23   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 03/22] bpf: Prepare bpf syscall to be used from kernel and user space Alexei Starovoitov
2021-05-11 22:31   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 04/22] libbpf: Support for syscall program type Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 05/22] selftests/bpf: Test " Alexei Starovoitov
2021-05-11 22:36   ` Andrii Nakryiko
2021-05-11 22:44     ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 06/22] bpf: Make btf_load command to be bpfptr_t compatible Alexei Starovoitov
2021-05-11 22:41   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 07/22] selftests/bpf: Test for btf_load command Alexei Starovoitov
2021-05-11 22:45   ` Andrii Nakryiko
2021-05-12  4:04     ` Alexei Starovoitov
2021-05-12 18:00       ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 08/22] bpf: Introduce fd_idx Alexei Starovoitov
2021-05-11 22:47   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 09/22] libbpf: Support for fd_idx Alexei Starovoitov
2021-05-11 22:57   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 10/22] bpf: Add bpf_btf_find_by_name_kind() helper Alexei Starovoitov
2021-05-11 23:02   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 11/22] bpf: Add bpf_sys_close() helper Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 12/22] libbpf: Change the order of data and text relocations Alexei Starovoitov
2021-05-11 23:06   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 13/22] libbpf: Add bpf_object pointer to kernel_supports() Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 14/22] libbpf: Generate loader program out of BPF ELF file Alexei Starovoitov
2021-05-11 23:22   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 15/22] libbpf: Use fd_array only with gen_loader Alexei Starovoitov
2021-05-11 23:24   ` Andrii Nakryiko
2021-05-12  4:17     ` Alexei Starovoitov [this message]
2021-05-12 18:11       ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 16/22] libbpf: Cleanup temp FDs when intermediate sys_bpf fails Alexei Starovoitov
2021-05-11 23:34   ` Andrii Nakryiko
2021-05-12  4:33     ` Alexei Starovoitov
2021-05-08  3:48 ` [PATCH v4 bpf-next 17/22] libbpf: Introduce bpf_map__get_initial_value() Alexei Starovoitov
2021-05-11 23:39   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 18/22] bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command Alexei Starovoitov
2021-05-12  4:17   ` Andrii Nakryiko
2021-05-12 18:43     ` Alexei Starovoitov
2021-05-12 18:55       ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 19/22] selftests/bpf: Convert few tests to light skeleton Alexei Starovoitov
2021-05-12  4:19   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 20/22] selftests/bpf: Convert atomics test " Alexei Starovoitov
2021-05-12  4:21   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 21/22] selftests/bpf: Convert test printk to use rodata Alexei Starovoitov
2021-05-12  4:23   ` Andrii Nakryiko
2021-05-08  3:48 ` [PATCH v4 bpf-next 22/22] selftests/bpf: Convert test trace_printk to lskel Alexei Starovoitov
2021-05-12  4:24   ` Andrii Nakryiko

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