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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf-next 3/7] libbpf: factor out common logic of testing and closing FD
Date: Tue, 18 Aug 2020 14:33:52 -0700	[thread overview]
Message-ID: <20200818213356.2629020-4-andriin@fb.com> (raw)
In-Reply-To: <20200818213356.2629020-1-andriin@fb.com>

Factor out common piece of logic that detects support for a feature based on
successfully created FD. Also take care of closing FD, if it was created.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/libbpf.c | 70 ++++++++++--------------------------------
 1 file changed, 17 insertions(+), 53 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 9cf22361f945..ab0c3a409eea 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3431,6 +3431,13 @@ bpf_object__probe_loading(struct bpf_object *obj)
 	return 0;
 }
 
+static int probe_fd(int fd)
+{
+	if (fd >= 0)
+		close(fd);
+	return fd >= 0;
+}
+
 static int probe_kern_prog_name(void)
 {
 	struct bpf_load_program_attr attr;
@@ -3449,12 +3456,7 @@ static int probe_kern_prog_name(void)
 	attr.license = "GPL";
 	attr.name = "test";
 	ret = bpf_load_program_xattr(&attr, NULL, 0);
-	if (ret >= 0) {
-		close(ret);
-		return 1;
-	}
-
-	return 0;
+	return probe_fd(ret);
 }
 
 static int probe_kern_global_data(void)
@@ -3495,12 +3497,7 @@ static int probe_kern_global_data(void)
 
 	ret = bpf_load_program_xattr(&prg_attr, NULL, 0);
 	close(map);
-	if (ret >= 0) {
-		close(ret);
-		return 1;
-	}
-
-	return 0;
+	return probe_fd(ret);
 }
 
 static int probe_kern_btf_func(void)
@@ -3516,16 +3513,9 @@ static int probe_kern_btf_func(void)
 		/* FUNC x */                                    /* [3] */
 		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
 	};
-	int btf_fd;
 
-	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-				      strs, sizeof(strs));
-	if (btf_fd >= 0) {
-		close(btf_fd);
-		return 1;
-	}
-
-	return 0;
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
 }
 
 static int probe_kern_btf_func_global(void)
@@ -3541,16 +3531,9 @@ static int probe_kern_btf_func_global(void)
 		/* FUNC x BTF_FUNC_GLOBAL */                    /* [3] */
 		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
 	};
-	int btf_fd;
 
-	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-				      strs, sizeof(strs));
-	if (btf_fd >= 0) {
-		close(btf_fd);
-		return 1;
-	}
-
-	return 0;
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
 }
 
 static int probe_kern_btf_datasec(void)
@@ -3567,16 +3550,9 @@ static int probe_kern_btf_datasec(void)
 		BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
 		BTF_VAR_SECINFO_ENC(2, 0, 4),
 	};
-	int btf_fd;
 
-	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
-				      strs, sizeof(strs));
-	if (btf_fd >= 0) {
-		close(btf_fd);
-		return 1;
-	}
-
-	return 0;
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
 }
 
 static int probe_kern_array_mmap(void)
@@ -3588,14 +3564,8 @@ static int probe_kern_array_mmap(void)
 		.value_size = sizeof(int),
 		.max_entries = 1,
 	};
-	int fd;
 
-	fd = bpf_create_map_xattr(&attr);
-	if (fd >= 0) {
-		close(fd);
-		return 1;
-	}
-	return 0;
+	return probe_fd(bpf_create_map_xattr(&attr));
 }
 
 static int probe_kern_exp_attach_type(void)
@@ -3605,7 +3575,6 @@ static int probe_kern_exp_attach_type(void)
 		BPF_MOV64_IMM(BPF_REG_0, 0),
 		BPF_EXIT_INSN(),
 	};
-	int fd;
 
 	memset(&attr, 0, sizeof(attr));
 	/* use any valid combination of program type and (optional)
@@ -3619,12 +3588,7 @@ static int probe_kern_exp_attach_type(void)
 	attr.insns_cnt = ARRAY_SIZE(insns);
 	attr.license = "GPL";
 
-	fd = bpf_load_program_xattr(&attr, NULL, 0);
-	if (fd >= 0) {
-		close(fd);
-		return 1;
-	}
-	return 0;
+	return probe_fd(bpf_load_program_xattr(&attr, NULL, 0));
 }
 
 enum kern_feature_result {
-- 
2.24.1


  parent reply	other threads:[~2020-08-18 21:34 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-18 21:33 [PATCH bpf-next 0/7] libbpf feature probing and sanitization improvements Andrii Nakryiko
2020-08-18 21:33 ` [PATCH bpf-next 1/7] libbpf: disable -Wswitch-enum compiler warning Andrii Nakryiko
2020-08-19  1:23   ` Yonghong Song
2020-08-19  1:39     ` Andrii Nakryiko
2020-08-19  5:44       ` Yonghong Song
2020-08-18 21:33 ` [PATCH bpf-next 2/7] libbpf: make kernel feature probing lazy Andrii Nakryiko
2020-08-18 21:33 ` Andrii Nakryiko [this message]
2020-08-18 21:33 ` [PATCH bpf-next 4/7] libbpf: sanitize BPF program code for bpf_probe_read_{kernel,user}[_str] Andrii Nakryiko
2020-08-19  1:42   ` Yonghong Song
2020-08-19 20:11     ` Andrii Nakryiko
2020-08-19 20:15       ` Alexei Starovoitov
2020-08-19 20:23         ` Andrii Nakryiko
2020-08-18 21:33 ` [PATCH bpf-next 5/7] selftests/bpf: fix test_vmlinux test to use bpf_probe_read_user() Andrii Nakryiko
2020-08-18 21:33 ` [PATCH bpf-next 6/7] libbpf: switch tracing and CO-RE helper macros to bpf_probe_read_kernel() Andrii Nakryiko
2020-08-18 21:33 ` [PATCH bpf-next 7/7] libbpf: detect minimal BTF support and skip BTF loading, if missing Andrii Nakryiko
2020-08-19  0:24 ` [PATCH bpf-next 0/7] libbpf feature probing and sanitization improvements Alexei Starovoitov

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