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SubjectRe: [PATCH v3 2/5] bpf: Simplify bpf_load_program() error handling in the library
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On 2017/2/8 4:56, Mickaël Salaün wrote:
> Do not call a second time bpf(2) when a program load failed.

BPF_PROG_LOAD should success most of the time. Setting log_level to
0 by default and require log buffer when failure can make it faster
in normal case.

Thank you.

> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Cc: Alexei Starovoitov <ast@fb.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Wang Nan <wangnan0@huawei.com>
> ---
> tools/lib/bpf/bpf.c | 18 ++++++------------
> 1 file changed, 6 insertions(+), 12 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 3ddb58a36d3c..fda3f494f1cd 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -73,7 +73,6 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
> size_t insns_cnt, char *license,
> __u32 kern_version, char *log_buf, size_t log_buf_sz)
> {
> - int fd;
> union bpf_attr attr;
>
> bzero(&attr, sizeof(attr));
> @@ -81,20 +80,15 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
> attr.insn_cnt = (__u32)insns_cnt;
> attr.insns = ptr_to_u64(insns);
> attr.license = ptr_to_u64(license);
> - attr.log_buf = ptr_to_u64(NULL);
> - attr.log_size = 0;
> - attr.log_level = 0;
> + attr.log_buf = ptr_to_u64(log_buf);
> + attr.log_size = log_buf_sz;
> attr.kern_version = kern_version;
>
> - fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
> - if (fd >= 0 || !log_buf || !log_buf_sz)
> - return fd;
> + if (log_buf && log_buf_sz > 0) {
> + attr.log_level = 1;
> + log_buf[0] = 0;
> + }
>
> - /* Try again with log */
> - attr.log_buf = ptr_to_u64(log_buf);
> - attr.log_size = log_buf_sz;
> - attr.log_level = 1;
> - log_buf[0] = 0;
> return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
> }
>


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