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| author | Sam James <sam@gentoo.org> | 2024-08-13 20:49:06 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-08-15 15:56:40 -0700 |
| commit | fab45b962749184e1a1a57c7c583782b78fad539 (patch) | |
| tree | 352ddc034d276ddd160b54ff46f12c43d34554de /tools/lib | |
| parent | febb6f3e3ac196602cca5738d8a189d57392324a (diff) | |
| download | linux-stable-fab45b962749184e1a1a57c7c583782b78fad539.tar.gz linux-stable-fab45b962749184e1a1a57c7c583782b78fad539.tar.bz2 linux-stable-fab45b962749184e1a1a57c7c583782b78fad539.zip | |
libbpf: Workaround -Wmaybe-uninitialized false positive
In `elf_close`, we get this with GCC 15 -O3 (at least):
```
In function ‘elf_close’,
inlined from ‘elf_close’ at elf.c:53:6,
inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
elf.c:57:9: warning: ‘elf_fd.elf’ may be used uninitialized [-Wmaybe-uninitialized]
57 | elf_end(elf_fd->elf);
| ^~~~~~~~~~~~~~~~~~~~
elf.c: In function ‘elf_find_func_offset_from_file’:
elf.c:377:23: note: ‘elf_fd.elf’ was declared here
377 | struct elf_fd elf_fd;
| ^~~~~~
In function ‘elf_close’,
inlined from ‘elf_close’ at elf.c:53:6,
inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
elf.c:58:9: warning: ‘elf_fd.fd’ may be used uninitialized [-Wmaybe-uninitialized]
58 | close(elf_fd->fd);
| ^~~~~~~~~~~~~~~~~
elf.c: In function ‘elf_find_func_offset_from_file’:
elf.c:377:23: note: ‘elf_fd.fd’ was declared here
377 | struct elf_fd elf_fd;
| ^~~~~~
```
In reality, our use is fine, it's just that GCC doesn't model errno
here (see linked GCC bug). Suppress -Wmaybe-uninitialized accordingly
by initializing elf_fd.fd to -1 and elf_fd.elf to NULL.
I've done this in two other functions as well given it could easily
occur there too (same access/use pattern).
Signed-off-by: Sam James <sam@gentoo.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://gcc.gnu.org/PR114952
Link: https://lore.kernel.org/bpf/14ec488a1cac02794c2fa2b83ae0cef1bce2cb36.1723578546.git.sam@gentoo.org
Diffstat (limited to 'tools/lib')
| -rw-r--r-- | tools/lib/bpf/elf.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c index c92e02394159..b5ab1cb13e5e 100644 --- a/tools/lib/bpf/elf.c +++ b/tools/lib/bpf/elf.c @@ -28,6 +28,9 @@ int elf_open(const char *binary_path, struct elf_fd *elf_fd) int fd, ret; Elf *elf; + elf_fd->elf = NULL; + elf_fd->fd = -1; + if (elf_version(EV_CURRENT) == EV_NONE) { pr_warn("elf: failed to init libelf for %s\n", binary_path); return -LIBBPF_ERRNO__LIBELF; |