From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754710Ab0EUKoL (ORCPT ); Fri, 21 May 2010 06:44:11 -0400 Received: from mail-ww0-f46.google.com ([74.125.82.46]:37665 "EHLO mail-ww0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753136Ab0EUKoI (ORCPT ); Fri, 21 May 2010 06:44:08 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Ixe4DLCYA3bEzWKqdIIkOv6UeU7rx7nRdR5prX5B50UcWhtf/bWEZJnQerq3FR31o0 FqiffL8fVNsqOcs3+x+vSY3zXFh5Qkh3dpgGuZt2sDMtFBxhP7IESAo7Ta/diR6BvOQo tW3edX+ZUq2ovPpwQmvpNoHx8tyd3HIB/M5tg= Date: Fri, 21 May 2010 12:43:54 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo , Steven Rostedt , LKML Subject: Re: [PATCH 02b/10] perf, trace: Fix probe unregister race Message-ID: <20100521104352.GH30108@nowhere> References: <20100521090201.326791353@chello.nl> <20100521090710.473188012@chello.nl> <1274438476.1674.1702.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1274438476.1674.1702.camel@laptop> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Acked-by: Frederic Weisbecker (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); > } > > >