On 03/25, Andrii Nakryiko wrote:
> On Wed, Mar 25, 2020 at 9:20 AM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
> >
> > For each prog/btf load we allocate and free 16 megs of verifier buffer.
> > On production systems it doesn't really make sense because the
> > programs/btf have gone through extensive testing and (mostly) guaranteed
> > to successfully load.
> >
> > Let's assume successful case by default and skip buffer allocation
> > on the first try. If there is an error, start with BPF_LOG_BUF_SIZE
> > and double it on each ENOSPC iteration.
> >
> > v2:
> > * Don't allocate the buffer at all on the first try (Andrii Nakryiko)
> >
> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> > ---
> > tools/lib/bpf/btf.c | 20 +++++++++++++++-----
> > tools/lib/bpf/libbpf.c | 22 ++++++++++++++--------
> > 2 files changed, 29 insertions(+), 13 deletions(-)
> >
> > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > index 3d1c25fc97ae..bfef3d606b54 100644
> > --- a/tools/lib/bpf/btf.c
> > +++ b/tools/lib/bpf/btf.c
> > @@ -657,22 +657,32 @@ int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
> >
> > int btf__load(struct btf *btf)
> > {
> > - __u32 log_buf_size = BPF_LOG_BUF_SIZE;
> > + __u32 log_buf_size = 0;
> > char *log_buf = NULL;
> > int err = 0;
> >
> > if (btf->fd >= 0)
> > return -EEXIST;
> >
> > - log_buf = malloc(log_buf_size);
> > - if (!log_buf)
> > - return -ENOMEM;
> > +retry_load:
> > + if (log_buf_size) {
> > + log_buf = malloc(log_buf_size);
> > + if (!log_buf)
> > + return -ENOMEM;
> >
> > - *log_buf = 0;
> > + *log_buf = 0;
> > + }
> >
> > btf->fd = bpf_load_btf(btf->data, btf->data_size,
> > log_buf, log_buf_size, false);
> > if (btf->fd < 0) {
> > + if (!log_buf || errno == ENOSPC) {
> > + log_buf_size = max((__u32)BPF_LOG_BUF_SIZE,
> > + log_buf_size << 1);
> > + free(log_buf);
> > + goto retry_load;
> > + }
> > +
> > err = -errno;
> > pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
> > if (*log_buf)
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 085e41f9b68e..b2fd43a03708 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -4855,8 +4855,8 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
> > {
> > struct bpf_load_program_attr load_attr;
> > char *cp, errmsg[STRERR_BUFSIZE];
> > - int log_buf_size = BPF_LOG_BUF_SIZE;
> > - char *log_buf;
> > + size_t log_buf_size = 0;
> > + char *log_buf = NULL;
> > int btf_fd, ret;
> >
> > if (!insns || !insns_cnt)
> > @@ -4896,22 +4896,28 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
> > load_attr.prog_flags = prog->prog_flags;
> >
> > retry_load:
> > - log_buf = malloc(log_buf_size);
> > - if (!log_buf)
> > - pr_warn("Alloc log buffer for bpf loader error, continue without log\n");
> > + if (log_buf_size) {
> > + log_buf = malloc(log_buf_size);
> > + if (!log_buf)
> > + pr_warn("Alloc log buffer for bpf loader error, continue without log\n");
> > +
>
> considering that log_buf is not allocated first time, if it fails to
> allocate on retry then it should be an error, no?
>
> Otherwise looks good, please add my ack after fixing this:
>
> Acked-by: Andrii Nakryiko <andriin@xxxxxx>
Thx, will respin a v3. Returning -ENOMEM also makes it more consistent with
btf retry logic.
> > + *log_buf = 0;
> > + }
> >
> > ret = bpf_load_program_xattr(&load_attr, log_buf, log_buf_size);
> >
> > if (ret >= 0) {
> > - if (load_attr.log_level)
> > + if (log_buf && load_attr.log_level)
> > pr_debug("verifier log:\n%s", log_buf);
> > *pfd = ret;
> > ret = 0;
> > goto out;
> > }
> >
> > - if (errno == ENOSPC) {
> > - log_buf_size <<= 1;
> > + if (!log_buf || errno == ENOSPC) {
> > + log_buf_size = max((size_t)BPF_LOG_BUF_SIZE,
> > + log_buf_size << 1);
> > +
> > free(log_buf);
> > goto retry_load;
> > }
> > --
> > 2.25.1.696.g5e7596f4ac-goog
> >
