[PATCH v3 2/5] bpf: Simplify bpf_load_program() error handling in the library

From: MickaÃl SalaÃn
Date: Tue Feb 07 2017 - 15:57:07 EST


Do not call a second time bpf(2) when a program load failed.

Signed-off-by: MickaÃl SalaÃn <mic@xxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
---
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));
}

--
2.11.0