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| author | Wang Nan <wangnan0@huawei.com> | 2015-07-01 02:13:49 +0000 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2015-08-06 15:27:37 -0300 |
| commit | 098d2164e3441c252eaa28906d45e16b7bf1bd2b (patch) | |
| tree | 394b769483a65287f8586ce693518a11ed1a7260 /include/linux/trace_events.h | |
| parent | 834fd46ddb50953cf3fd9caa3f35485715c62ea3 (diff) | |
| download | lwn-098d2164e3441c252eaa28906d45e16b7bf1bd2b.tar.gz lwn-098d2164e3441c252eaa28906d45e16b7bf1bd2b.zip | |
bpf: Use correct #ifdef controller for trace_call_bpf()
Commit e1abf2cc8d5d80b41c4419368ec743ccadbb131e ("bpf: Fix the build on
BPF_SYSCALL=y && !CONFIG_TRACING kernels, make it more configurable")
updated the building condition of bpf_trace.o from CONFIG_BPF_SYSCALL
to CONFIG_BPF_EVENTS, but the corresponding #ifdef controller in
trace_events.h for trace_call_bpf() was not changed. Which, in theory,
is incorrect.
With current Kconfigs, we can create a .config with CONFIG_BPF_SYSCALL=y
and CONFIG_BPF_EVENTS=n by unselecting CONFIG_KPROBE_EVENT and
selecting CONFIG_BPF_SYSCALL. With these options, trace_call_bpf() will
be defined as an extern function, but if anyone calls it a symbol missing
error will be triggered since bpf_trace.o was not built.
This patch changes the #ifdef controller for trace_call_bpf() from
CONFIG_BPF_SYSCALL to CONFIG_BPF_EVENTS. I'll show its correctness:
Before this patch:
BPF_SYSCALL BPF_EVENTS trace_call_bpf bpf_trace.o
y y normal compiled
n n inline not compiled
y n normal not compiled (incorrect)
n y impossible (BPF_EVENTS depends on BPF_SYSCALL)
After this patch:
BPF_SYSCALL BPF_EVENTS trace_call_bpf bpf_trace.o
y y normal compiled
n n inline not compiled
y n inline not compiled (fixed)
n y impossible (BPF_EVENTS depends on BPF_SYSCALL)
So this patch doesn't break anything. QED.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'include/linux/trace_events.h')
| -rw-r--r-- | include/linux/trace_events.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 1063c850dbab..180dbf8720f9 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -542,7 +542,7 @@ event_trigger_unlock_commit_regs(struct trace_event_file *file, event_triggers_post_call(file, tt); } -#ifdef CONFIG_BPF_SYSCALL +#ifdef CONFIG_BPF_EVENTS unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx); #else static inline unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx) |