Messages in this thread | | | Date | Fri, 21 May 2010 12:43:54 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 02b/10] perf, trace: Fix probe unregister race |
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On Fri, May 21, 2010 at 12:41:16PM +0200, Peter Zijlstra wrote: > 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>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
(and you previous patches too)
> --- > 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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