Messages in this thread Patch in this message | | | Subject | [PATCH 02b/10] perf, trace: Fix probe unregister race | From | Peter Zijlstra <> | Date | Fri, 21 May 2010 12:41:16 +0200 |
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tracepoint_probe_unregister() does not synchronize against the probe callbacks, so do that explicitly. This properly serializes the callbacks and the free of the data used therein.
Also, use this_cpu_ptr() where possible.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- include/trace/ftrace.h | 2 +- kernel/trace/trace_event_perf.c | 10 ++++++++-- kernel/trace/trace_kprobe.c | 4 ++-- kernel/trace/trace_syscalls.c | 4 ++-- 4 files changed, 13 insertions(+), 7 deletions(-)
Index: linux-2.6/include/trace/ftrace.h =================================================================== --- linux-2.6.orig/include/trace/ftrace.h +++ linux-2.6/include/trace/ftrace.h @@ -791,7 +791,7 @@ perf_trace_templ_##call(struct ftrace_ev \ { assign; } \ \ - head = per_cpu_ptr(event_call->perf_events, smp_processor_id());\ + head = this_cpu_ptr(event_call->perf_events); \ perf_trace_buf_submit(entry, __entry_size, rctx, __addr, \ __count, __regs, head); \ } Index: linux-2.6/kernel/trace/trace_event_perf.c =================================================================== --- linux-2.6.orig/kernel/trace/trace_event_perf.c +++ linux-2.6/kernel/trace/trace_event_perf.c @@ -109,7 +109,7 @@ int perf_trace_enable(struct perf_event if (WARN_ON_ONCE(!list)) return -EINVAL; - list = per_cpu_ptr(list, smp_processor_id()); + list = this_cpu_ptr(list); hlist_add_head_rcu(&p_event->hlist_entry, list); return 0; @@ -130,6 +130,12 @@ void perf_trace_destroy(struct perf_even tp_event->perf_event_disable(tp_event); + /* + * Ensure our callback won't be called anymore. See + * tracepoint_probe_unregister() and __DO_TRACE(). + */ + synchronize_sched(); + free_percpu(tp_event->perf_events); tp_event->perf_events = NULL; @@ -156,7 +162,7 @@ __kprobes void *perf_trace_buf_prepare(i if (*rctxp < 0) return NULL; - raw_data = per_cpu_ptr(perf_trace_buf[*rctxp], smp_processor_id()); + raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); /* zero the dead bytes from align to not leak stack to user */ memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); Index: linux-2.6/kernel/trace/trace_kprobe.c =================================================================== --- linux-2.6.orig/kernel/trace/trace_kprobe.c +++ linux-2.6/kernel/trace/trace_kprobe.c @@ -1362,7 +1362,7 @@ static __kprobes void kprobe_perf_func(s for (i = 0; i < tp->nr_args; i++) call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset); - head = per_cpu_ptr(call->perf_events, smp_processor_id()); + head = this_cpu_ptr(call->perf_events); perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head); } @@ -1395,7 +1395,7 @@ static __kprobes void kretprobe_perf_fun for (i = 0; i < tp->nr_args; i++) call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset); - head = per_cpu_ptr(call->perf_events, smp_processor_id()); + head = this_cpu_ptr(call->perf_events); perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head); } Index: linux-2.6/kernel/trace/trace_syscalls.c =================================================================== --- linux-2.6.orig/kernel/trace/trace_syscalls.c +++ linux-2.6/kernel/trace/trace_syscalls.c @@ -469,7 +469,7 @@ static void perf_syscall_enter(struct pt syscall_get_arguments(current, regs, 0, sys_data->nb_args, (unsigned long *)&rec->args); - head = per_cpu_ptr(sys_data->enter_event->perf_events, smp_processor_id()); + head = this_cpu_ptr(sys_data->enter_event->perf_events); perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head); } @@ -545,7 +545,7 @@ static void perf_syscall_exit(struct pt_ rec->nr = syscall_nr; rec->ret = syscall_get_return_value(current, regs); - head = per_cpu_ptr(sys_data->exit_event->perf_events, smp_processor_id()); + head = this_cpu_ptr(sys_data->exit_event->perf_events); perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head); }
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