bpf_trace: Make dependent on PERF_EVENTS

Arnd Bergmann reported: In my ARM randconfig tests, I'm getting a build error for newly added code in bpf_perf_event_read and bpf_perf_event_output whenever CONFIG_PERF_EVENTS is disabled: kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read': kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu' if (event->oncpu != smp_processor_id() || ^ kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu' event->pmu->count) This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT is disabled. I'm not sure if that is a configuration we care about, otherwise we could prevent this case from occuring by adding Kconfig dependencies. Looking at this further, it's really that UPROBE_EVENT enables PERF_EVENTS. By just having BPF_EVENTS depend on PERF_EVENTS, then all is fine.

SRSteven Rostedt committed 11 years ago