From e87c6bc3852b981e71c757be20771546ce9f76f3 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Mon, 23 Oct 2017 23:53:08 -0700 Subject: bpf: permit multiple bpf attachments for a single perf event This patch enables multiple bpf attachments for a kprobe/uprobe/tracepoint single trace event. Each trace_event keeps a list of attached perf events. When an event happens, all attached bpf programs will be executed based on the order of attachment. A global bpf_event_mutex lock is introduced to protect prog_array attaching and detaching. An alternative will be introduce a mutex lock in every trace_event_call structure, but it takes a lot of extra memory. So a global bpf_event_mutex lock is a good compromise. The bpf prog detachment involves allocation of memory. If the allocation fails, a dummy do-nothing program will replace to-be-detached program in-place. Signed-off-by: Yonghong Song Acked-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Signed-off-by: David S. Miller --- include/trace/perf.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/trace/perf.h') diff --git a/include/trace/perf.h b/include/trace/perf.h index 04fe68bb..14f127b6 100644 --- a/include/trace/perf.h +++ b/include/trace/perf.h @@ -34,7 +34,6 @@ perf_trace_##call(void *__data, proto) \ struct trace_event_call *event_call = __data; \ struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\ struct trace_event_raw_##call *entry; \ - struct bpf_prog *prog = event_call->prog; \ struct pt_regs *__regs; \ u64 __count = 1; \ struct task_struct *__task = NULL; \ @@ -46,8 +45,9 @@ perf_trace_##call(void *__data, proto) \ __data_size = trace_event_get_offsets_##call(&__data_offsets, args); \ \ head = this_cpu_ptr(event_call->perf_events); \ - if (!prog && __builtin_constant_p(!__task) && !__task && \ - hlist_empty(head)) \ + if (!bpf_prog_array_valid(event_call) && \ + __builtin_constant_p(!__task) && !__task && \ + hlist_empty(head)) \ return; \ \ __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\ -- cgit v1.1