netdev - [PATCH net-next v1 5/7] bpf: Simplify bpf_load_program() error handling in the library

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Date:   Mon,  6 Feb 2017 00:14:26 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     linux-kernel@...r.kernel.org
Cc:     Mickaël Salaün <mic@...ikod.net>,
        netdev@...r.kernel.org, Alexei Starovoitov <ast@...com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Wang Nan <wangnan0@...wei.com>
Subject: [PATCH net-next v1 5/7] bpf: Simplify bpf_load_program() error handling in the library

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

Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Cc: Alexei Starovoitov <ast@...com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Wang Nan <wangnan0@...wei.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));
 }
 
-- 
2.11.0