linux-kernel - [PATCH 4.19 42/63] bpf: libbpf: retry loading program on EAGAIN

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Date:   Sun, 29 Sep 2019 15:54:15 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lorenz Bauer <lmb@...udflare.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 42/63] bpf: libbpf: retry loading program on EAGAIN

From: Lorenz Bauer <lmb@...udflare.com>

[ Upstream commit 86edaed379632e216a97e6bcef9f498b64522d50 ]

Commit c3494801cd17 ("bpf: check pending signals while
verifying programs") makes it possible for the BPF_PROG_LOAD
to fail with EAGAIN. Retry unconditionally in this case.

Fixes: c3494801cd17 ("bpf: check pending signals while verifying programs")
Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bpf/bpf.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index dd0b68d1f4be0..482025b728399 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -75,6 +75,17 @@ static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
 	return syscall(__NR_bpf, cmd, attr, size);
 }
 
+static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size)
+{
+	int fd;
+
+	do {
+		fd = sys_bpf(BPF_PROG_LOAD, attr, size);
+	} while (fd < 0 && errno == EAGAIN);
+
+	return fd;
+}
+
 int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
 {
 	__u32 name_len = create_attr->name ? strlen(create_attr->name) : 0;
@@ -218,7 +229,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 	memcpy(attr.prog_name, load_attr->name,
 	       min(name_len, BPF_OBJ_NAME_LEN - 1));
 
-	fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+	fd = sys_bpf_prog_load(&attr, sizeof(attr));
 	if (fd >= 0 || !log_buf || !log_buf_sz)
 		return fd;
 
@@ -227,7 +238,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 	attr.log_size = log_buf_sz;
 	attr.log_level = 1;
 	log_buf[0] = 0;
-	return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+	return sys_bpf_prog_load(&attr, sizeof(attr));
 }
 
 int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
@@ -268,7 +279,7 @@ int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
 	attr.kern_version = kern_version;
 	attr.prog_flags = strict_alignment ? BPF_F_STRICT_ALIGNMENT : 0;
 
-	return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+	return sys_bpf_prog_load(&attr, sizeof(attr));
 }
 
 int bpf_map_update_elem(int fd, const void *key, const void *value,
-- 
2.20.1