Detected by LGTM static analyze in Github repo, fix potential multiplication
overflow before result is casted to size_t.

Fixes: 8505e870 ("libbpf: Implement generalized .BTF.ext func/line info adjustment")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904041611.1695163-2-andriin@fb.com

Another issue of __u64 needing either %lu or %llu, depending on the
architecture. Fix with cast to `unsigned long long`.

Fixes: 7e06aad5 ("libbpf: Add multi-prog section support for struct_ops")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904041611.1695163-1-andriin@fb.com

BPF program title is ambigious and misleading term. It is ELF section name, so
let's just call it that and deprecate bpf_program__title() API in favor of
bpf_program__section_name().

Additionally, using bpf_object__find_program_by_title() is now inherently
dangerous and ambiguous, as multiple BPF program can have the same section
name. So deprecate this API as well and recommend to switch to non-ambiguous
bpf_object__find_program_by_name().

Internally, clean up usage and mis-usage of BPF program section name for
denoting BPF program name. Shorten the field name to prog->sec_name to be
consistent with all other prog->sec_* variables.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-11-andriin@fb.com

Adjust struct_ops handling code to work with multi-program ELF sections
properly.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-7-andriin@fb.com

Complete multi-prog sections and multi sub-prog support in libbpf by properly
adjusting .BTF.ext's line and function information. Mark exposed
btf_ext__reloc_func_info() and btf_ext__reloc_func_info() APIs as deprecated.
These APIs have simplistic assumption that all sub-programs are going to be
appended to all main BPF programs, which doesn't hold in real life. It's
unlikely there are any users of this API, as it's very libbpf
internals-specific.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-6-andriin@fb.com

This patch implements general and correct logic for bpf-to-bpf sub-program
calls. Only sub-programs used (called into) from entry-point (main) BPF
program are going to be appended at the end of main BPF program. This ensures
that BPF verifier won't encounter any dead code due to copying unreferenced
sub-program. This change means that each entry-point (main) BPF program might
have a different set of sub-programs appended to it and potentially in
different order. This has implications on how sub-program call relocations
need to be handled, described below.

All relocations are now split into two categores: data references (maps and
global variables) and code references (sub-program calls). This distinction is
important because data references need to be relocated just once per each BPF
program and sub-program. These relocation are agnostic to instruction
locations, because they are not code-relative and they are relocating against
static targets (maps, variables with fixes offsets, etc).

Sub-program RELO_CALL relocations, on the other hand, are highly-dependent on
code position, because they are recorded as instruction-relative offset. So
BPF sub-programs (those that do calls into other sub-programs) can't be
relocated once, they need to be relocated each time such a sub-program is
appended at the end of the main entry-point BPF program. As mentioned above,
each main BPF program might have different subset and differen order of
sub-programs, so call relocations can't be done just once. Splitting data
reference and calls relocations as described above allows to do this
efficiently and cleanly.

bpf_object__find_program_by_name() will now ignore non-entry BPF programs.
Previously one could have looked up '.text' fake BPF program, but the
existence of such BPF program was always an implementation detail and you
can't do much useful with it. Now, though, all non-entry sub-programs get
their own BPF program with name corresponding to a function name, so there is
no more '.text' name for BPF program. This means there is no regression,
effectively, w.r.t.  API behavior. But this is important aspect to highlight,
because it's going to be critical once libbpf implements static linking of BPF
programs. Non-entry static BPF programs will be allowed to have conflicting
names, but global and main-entry BPF program names should be unique. Just like
with normal user-space linking process. So it's important to restrict this
aspect right now, keep static and non-entry functions as internal
implementation details, and not have to deal with regressions in behavior
later.

This patch leaves .BTF.ext adjustment as is until next patch.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-5-andriin@fb.com

Fix up CO-RE relocation code to handle relocations against ELF sections
containing multiple BPF programs. This requires lookup of a BPF program by its
section name and instruction index it contains. While it could have been done
as a simple loop, it could run into performance issues pretty quickly, as
number of CO-RE relocations can be quite large in real-world applications, and
each CO-RE relocation incurs BPF program look up now. So instead of simple
loop, implement a binary search by section name + insn offset.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-4-andriin@fb.com

Teach libbpf how to parse code sections into potentially multiple bpf_program
instances, based on ELF FUNC symbols. Each BPF program will keep track of its
position within containing ELF section for translating section instruction
offsets into program instruction offsets: regardless of BPF program's location
in ELF section, it's first instruction is always at local instruction offset
0, so when libbpf is working with relocations (which use section-based
instruction offsets) this is critical to make proper translations.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-3-andriin@fb.com

libbpf ELF parsing logic might need symbols available before ELF parsing is
completed, so we need to make sure that symbols table section is found in
a separate pass before all the subsequent sections are processed.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-2-andriin@fb.com

Pass request to load program as sleepable via ".s" suffix in the section name.
If it happens in the future that all map types and helpers are allowed with
BPF_F_SLEEPABLE flag "fmod_ret/" and "lsm/" can be aliased to "fmod_ret.s/" and
"lsm.s/" to make all lsm and fmod_ret programs sleepable by default. The fentry
and fexit programs would always need to have sleepable vs non-sleepable
distinction, since not all fentry/fexit progs will be attached to sleepable
kernel functions.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NKP Singh <kpsingh@google.com>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-5-alexei.starovoitov@gmail.com

Fix compilation warnings due to __u64 defined differently as `unsigned long`
or `unsigned long long` on different architectures (e.g., ppc64le differs from
x86-64). Also cast one argument to size_t to fix printf warning of similar
nature.

Fixes: eacaaed7 ("libbpf: Implement enum value-based CO-RE relocations")
Fixes: 50e09460 ("libbpf: Skip well-known ELF sections when iterating ELF")
Reported-by: NNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200827041109.3613090-1-andriin@fb.com

There are code paths where EINVAL is returned directly without setting
errno. In that case, errno could be 0, which would mask the
failure. For example, if a careless programmer set log_level to 10000
out of laziness, they would have to spend a long time trying to figure
out why.

Fixes: 4f33ddb4 ("libbpf: Propagate EPERM to caller on program load")
Signed-off-by: NAlex Gartrell <alexgartrell@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200826075549.1858580-1-alexgartrell@gmail.com

Fix copy-paste error in types compatibility check. Local type is accidentally
used instead of target type for the very first type check strictness check.
This can result in potentially less strict candidate comparison. Fix the
error.

Fixes: 3fc32f40 ("libbpf: Implement type-based CO-RE relocations support")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821225653.2180782-1-andriin@fb.com

Some versions of GCC report uninitialized targ_spec usage. GCC is wrong, but
let's avoid unnecessary warnings.

Fixes: ddc7c304 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821225556.2178419-1-andriin@fb.com

Make libbpf logs follow similar pattern and provide more context like section
name or program name, where appropriate. Also, add BPF_INSN_SZ constant and
use it throughout to clean up code a little bit. This commit doesn't have any
functional changes and just removes some code changes out of the way before
bigger refactoring in libbpf internals.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820231250.1293069-6-andriin@fb.com

Skip and don't log ELF sections that libbpf knows about and ignores during ELF
processing. This allows to not unnecessarily log details about those ELF
sections and cleans up libbpf debug log. Ignored sections include DWARF data,
string table, empty .text section and few special (e.g., .llvm_addrsig)
useless sections.

With such ELF sections out of the way, log unrecognized ELF sections at
pr_info level to increase visibility.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820231250.1293069-5-andriin@fb.com

Factor out common ELF operations done throughout the libbpf. This simplifies
usage across multiple places in libbpf, as well as hide error reporting from
higher-level functions and make error logging more consistent.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820231250.1293069-3-andriin@fb.com

Add a set of APIs to perf_buffer manage to allow applications to integrate
perf buffer polling into existing epoll-based infrastructure. One example is
applications using libevent already and wanting to plug perf_buffer polling,
instead of relying on perf_buffer__poll() and waste an extra thread to do it.
But perf_buffer is still extremely useful to set up and consume perf buffer
rings even for such use cases.

So to accomodate such new use cases, add three new APIs:
  - perf_buffer__buffer_cnt() returns number of per-CPU buffers maintained by
    given instance of perf_buffer manager;
  - perf_buffer__buffer_fd() returns FD of perf_event corresponding to
    a specified per-CPU buffer; this FD is then polled independently;
  - perf_buffer__consume_buffer() consumes data from single per-CPU buffer,
    identified by its slot index.

To support a simpler, but less efficient, way to integrate perf_buffer into
external polling logic, also expose underlying epoll FD through
perf_buffer__epoll_fd() API. It will need to be followed by
perf_buffer__poll(), wasting extra syscall, or perf_buffer__consume(), wasting
CPU to iterate buffers with no data. But could be simpler and more convenient
for some cases.

These APIs allow for great flexiblity, but do not sacrifice general usability
of perf_buffer.

Also exercise and check new APIs in perf_buffer selftest.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NAlan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20200821165927.849538-1-andriin@fb.com

BPF_CALL | BPF_JMP32 is explicitly not allowed by verifier for BPF helper
calls, so don't detect it as a valid call. Also drop the check on func_id
pointer, as it's currently always non-null.

Fixes: 109cea5a ("libbpf: Sanitize BPF program code for bpf_probe_read_{kernel, user}[_str]")
Reported-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200820061411.1755905-1-andriin@fb.com

The error message emitted by bpf_object__init_user_btf_maps() was using the
wrong section ID.
Signed-off-by: NToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200819110534.9058-1-toke@redhat.com

Simplify the return expression.
Signed-off-by: NXu Wang <vulab@iscas.ac.cn>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200819025324.14680-1-vulab@iscas.ac.cn

Implement two relocations of a new enumerator value-based CO-RE relocation
kind: ENUMVAL_EXISTS and ENUMVAL_VALUE.

First, ENUMVAL_EXISTS, allows to detect the presence of a named enumerator
value in the target (kernel) BTF. This is useful to do BPF helper/map/program
type support detection from BPF program side. bpf_core_enum_value_exists()
macro helper is provided to simplify built-in usage.

Second, ENUMVAL_VALUE, allows to capture enumerator integer value and relocate
it according to the target BTF, if it changes. This is useful to have
a guarantee against intentional or accidental re-ordering/re-numbering of some
of the internal (non-UAPI) enumerations, where kernel developers don't care
about UAPI backwards compatiblity concerns. bpf_core_enum_value() allows to
capture this succinctly and use correct enum values in code.

LLVM uses ldimm64 instruction to capture enumerator value-based relocations,
so add support for ldimm64 instruction patching as well.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200819194519.3375898-5-andriin@fb.com

Implement support for TYPE_EXISTS/TYPE_SIZE/TYPE_ID_LOCAL/TYPE_ID_REMOTE
relocations. These are examples of type-based relocations, as opposed to
field-based relocations supported already. The difference is that they are
calculating relocation values based on the type itself, not a field within
a struct/union.

Type-based relos have slightly different semantics when matching local types
to kernel target types, see comments in bpf_core_types_are_compat() for
details. Their behavior on failure to find target type in kernel BTF also
differs. Instead of "poisoning" relocatable instruction and failing load
subsequently in kernel, they return 0 (which is rarely a valid return result,
so user BPF code can use that to detect success/failure of the relocation and
deal with it without extra "guarding" relocations). Also, it's always possible
to check existence of the type in target kernel with TYPE_EXISTS relocation,
similarly to a field-based FIELD_EXISTS.

TYPE_ID_LOCAL relocation is a bit special in that it always succeeds (barring
any libbpf/Clang bugs) and resolved to BTF ID using **local** BTF info of BPF
program itself. Tests in subsequent patches demonstrate the usage and
semantics of new relocations.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200819194519.3375898-2-andriin@fb.com

It's trivial to handle missing ELF_C_MMAP_READ support in libelf the way that
objtool has solved it in
("774bec3f objtool: Add fallback from ELF_C_READ_MMAP to ELF_C_READ").

So instead of having an entire feature detector for that, just do what objtool
does for perf and libbpf. And keep their Makefiles a bit simpler.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-5-andriin@fb.com

Most of libbpf source files already include libbpf_internal.h, so it's a good
place to centralize identifier poisoning. So move kernel integer type
poisoning there. And also add reallocarray to a poison list to prevent
accidental use of it. libbpf_reallocarray() should be used universally
instead.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-4-andriin@fb.com

Re-implement glibc's reallocarray() for libbpf internal-only use.
reallocarray(), unfortunately, is not available in all versions of glibc, so
requires extra feature detection and using reallocarray() stub from
<tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates build
of libbpf unnecessarily and is just a maintenance burden. Instead, it's
trivial to implement libbpf-specific internal version and use it throughout
libbpf.

Which is what this patch does, along with converting some realloc() uses that
should really have been reallocarray() in the first place.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com

Split the instruction patching logic into relocation value calculation and
application of relocation to instruction. Using this, evaluate relocation
against each matching candidate and validate that all candidates agree on
relocated value. If not, report ambiguity and fail load.

This logic is necessary to avoid dangerous (however unlikely) accidental match
against two incompatible candidate types. Without this change, libbpf will
pick a random type as *the* candidate and apply potentially invalid
relocation.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818223921.2911963-4-andriin@fb.com

Add logging of local/target type kind (struct/union/typedef/etc). Preserve
unresolved root type ID (for cases of typedef). Improve the format of CO-RE
reloc spec output format to contain only relevant and succinct info.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818223921.2911963-3-andriin@fb.com

Instead of printing out integer value of BTF kind, print out a string
representation of a kind.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818223921.2911963-2-andriin@fb.com

Detect whether a kernel supports any BTF at all, and if not, don't even
attempt loading BTF to avoid unnecessary log messages like:

  libbpf: Error loading BTF: Invalid argument(22)
  libbpf: Error loading .BTF into kernel: -22. BTF is optional, ignoring.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-8-andriin@fb.com

Add BPF program code sanitization pass, replacing calls to BPF
bpf_probe_read_{kernel,user}[_str]() helpers with bpf_probe_read[_str](), if
libbpf detects that kernel doesn't support new variants.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-5-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: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-4-andriin@fb.com

Turn libbpf's kernel feature probing into lazily-performed checks. This allows
to skip performing unnecessary feature checks, if a given BPF application
doesn't rely on a particular kernel feature. As we grow number of feature
probes, libbpf might perform less unnecessary syscalls and scale better with
number of feature probes long-term.

By decoupling feature checks from bpf_object, it's also possible to perform
feature probing from libbpf static helpers and low-level APIs, if necessary.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-3-andriin@fb.com

Replace a comma between expression statements by a semicolon.
Signed-off-by: NXu Wang <vulab@iscas.ac.cn>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200818071611.21923-1-vulab@iscas.ac.cn

BPF object files are always targeting 64-bit BPF target architecture, so
enforce that at BTF level as well.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-7-andriin@fb.com

Libbpf built in 32-bit mode should be careful about not conflating 64-bit BPF
pointers in BPF ELF file and host architecture pointers. This patch fixes
issue of incorrect initializating of map-in-map inner map slots due to such
difference.

Fixes: 646f02ff ("libbpf: Add BTF-defined map-in-map support")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-4-andriin@fb.com

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: NToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200813142905.160381-1-toke@redhat.com

Previous commit adjusted kernel uapi for map
element bpf iterator. This patch adjusted libbpf API
due to uapi change. bpftool and bpf_iter selftests
are also changed accordingly.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200805055058.1457623-1-yhs@fb.com

Add low-level bpf_link_detach() API. Also add higher-level bpf_link__detach()
one.
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NSong Liu <songliubraving@fb.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-3-andriin@fb.com

Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as
a pointer. It's a common mistake to eventually pass such malformed pointers
into xxx__destroy()/xxx__free() "destructors". So instead of fixing up
clean up code in selftests and user programs, handle such error pointers in
destructors themselves. This works beautifully for NULL pointers passed to
destructors, so might as well just work for error pointers.
Suggested-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729232148.896125-1-andriin@fb.com