| Message ID | 20200813142905.160381-1-toke@redhat.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] libbpf: Prevent overriding errno when logging errors | expand |
On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: > > Turns out there were a few more instances where libbpf didn't save the > errno before writing an error message, causing errno to be overridden by > the printf() return and the error disappearing if logging is enabled. > > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> > --- Acked-by: Andrii Nakryiko <andriin@fb.com> > tools/lib/bpf/libbpf.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 0a06124f7999..fd256440e233 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) > > map = bpf_create_map_xattr(&map_attr); > if (map < 0) { > - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); > + ret = -errno; > + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg)); fyi, libbpf_strerror_r() is smart enough to work with both negative and positive error numbers (it basically takes abs(err)), so no need to ensure it's positive here and below. > pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", > - __func__, cp, errno); > - return -errno; > + __func__, cp, -ret); > + return ret; > } > > insns[0].imm = map; > @@ -6012,9 +6013,10 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, > } > > if (bpf_obj_pin(prog->instances.fds[instance], path)) { > - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); > + err = -errno; > + cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg)); > pr_warn("failed to pin program: %s\n", cp); > - return -errno; > + return err; > } > pr_debug("pinned program '%s'\n", path); > > -- > 2.28.0 >
Andrii Nakryiko <andrii.nakryiko@gmail.com> writes: > On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: >> >> Turns out there were a few more instances where libbpf didn't save the >> errno before writing an error message, causing errno to be overridden by >> the printf() return and the error disappearing if logging is enabled. >> >> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> >> --- > > Acked-by: Andrii Nakryiko <andriin@fb.com> > >> tools/lib/bpf/libbpf.c | 12 +++++++----- >> 1 file changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index 0a06124f7999..fd256440e233 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) >> >> map = bpf_create_map_xattr(&map_attr); >> if (map < 0) { >> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); >> + ret = -errno; >> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg)); > > fyi, libbpf_strerror_r() is smart enough to work with both negative > and positive error numbers (it basically takes abs(err)), so no need > to ensure it's positive here and below. Noted. Although that also means it doesn't hurt either, I suppose; so not going to bother respinning this unless someone insists :) -Toke
On 8/13/20 9:52 PM, Toke Høiland-Jørgensen wrote: > Andrii Nakryiko <andrii.nakryiko@gmail.com> writes: >> On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: >>> >>> Turns out there were a few more instances where libbpf didn't save the >>> errno before writing an error message, causing errno to be overridden by >>> the printf() return and the error disappearing if logging is enabled. >>> >>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> >>> --- >> >> Acked-by: Andrii Nakryiko <andriin@fb.com> >> >>> tools/lib/bpf/libbpf.c | 12 +++++++----- >>> 1 file changed, 7 insertions(+), 5 deletions(-) >>> >>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >>> index 0a06124f7999..fd256440e233 100644 >>> --- a/tools/lib/bpf/libbpf.c >>> +++ b/tools/lib/bpf/libbpf.c >>> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) >>> >>> map = bpf_create_map_xattr(&map_attr); >>> if (map < 0) { >>> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); >>> + ret = -errno; >>> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg)); >> >> fyi, libbpf_strerror_r() is smart enough to work with both negative >> and positive error numbers (it basically takes abs(err)), so no need >> to ensure it's positive here and below. > > Noted. Although that also means it doesn't hurt either, I suppose; so > not going to bother respinning this unless someone insists :) Fixed up while applying, thanks!
Daniel Borkmann <daniel@iogearbox.net> writes: > On 8/13/20 9:52 PM, Toke Høiland-Jørgensen wrote: >> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes: >>> On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: >>>> >>>> Turns out there were a few more instances where libbpf didn't save the >>>> errno before writing an error message, causing errno to be overridden by >>>> the printf() return and the error disappearing if logging is enabled. >>>> >>>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> >>>> --- >>> >>> Acked-by: Andrii Nakryiko <andriin@fb.com> >>> >>>> tools/lib/bpf/libbpf.c | 12 +++++++----- >>>> 1 file changed, 7 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >>>> index 0a06124f7999..fd256440e233 100644 >>>> --- a/tools/lib/bpf/libbpf.c >>>> +++ b/tools/lib/bpf/libbpf.c >>>> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) >>>> >>>> map = bpf_create_map_xattr(&map_attr); >>>> if (map < 0) { >>>> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); >>>> + ret = -errno; >>>> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg)); >>> >>> fyi, libbpf_strerror_r() is smart enough to work with both negative >>> and positive error numbers (it basically takes abs(err)), so no need >>> to ensure it's positive here and below. >> >> Noted. Although that also means it doesn't hurt either, I suppose; so >> not going to bother respinning this unless someone insists :) > > Fixed up while applying, thanks! Great, thanks! -Toke
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0a06124f7999..fd256440e233 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) map = bpf_create_map_xattr(&map_attr); if (map < 0) { - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + ret = -errno; + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", - __func__, cp, errno); - return -errno; + __func__, cp, -ret); + return ret; } insns[0].imm = map; @@ -6012,9 +6013,10 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, } if (bpf_obj_pin(prog->instances.fds[instance], path)) { - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + err = -errno; + cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg)); pr_warn("failed to pin program: %s\n", cp); - return -errno; + return err; } pr_debug("pinned program '%s'\n", path);
Turns out there were a few more instances where libbpf didn't save the errno before writing an error message, causing errno to be overridden by the printf() return and the error disappearing if logging is enabled. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> --- tools/lib/bpf/libbpf.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)