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

[Greg Kroah-Hartman]

From: Lorenz Bauer <l...@cloudflare.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 <l...@cloudflare.com>
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Signed-off-by: Sasha Levin <sas...@kernel.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