From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757450AbaFSOMJ (ORCPT ); Thu, 19 Jun 2014 10:12:09 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.225]:3177 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754027AbaFSOMH (ORCPT ); Thu, 19 Jun 2014 10:12:07 -0400 Date: Thu, 19 Jun 2014 10:12:04 -0400 From: Steven Rostedt To: Steven Rostedt Cc: Linus Torvalds , LKML , Ingo Molnar , Andrew Morton , Oleg Nesterov Subject: Re: [GIT PULL] tracing: Cleanups and fixes to syscall tracepoints Message-ID: <20140619101204.2b0b3837@gandalf.local.home> In-Reply-To: <20140619095908.49dbc025@gandalf.local.home> References: <20140619095908.49dbc025@gandalf.local.home> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.130:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Please do not pull this. I just found out that it can break other archs as it uses TIF_SYSCALL_TRACEPOINT in generic code and not all archs define it. I'll work on a fix for this and send an update. -- Steve On Thu, 19 Jun 2014 09:59:08 -0400 Steven Rostedt wrote: > > Linus, > > This includes three patches from Oleg Nesterov. The first is a fix to a > race condition that happens between enabling/disabling syscall tracepoints > and new process creations (the check to go into the ptrace path for a process > can be set when it shouldn't, or not set when it should). Not a major bug > but one that should be fixed and even applied to stable. > > The other two patches are cleanup/fixes that are not that critical, but > for an -rc1 release would be nice to have. They both deal with syscall > tracepoints. > > I would have included these with my initial pull request, but as Oleg > posted his last version as a reply to the bottom of the patch 1/3 > thread, I missed it. > > Please pull the latest trace-fixes-v3.16-rc1 tree, which can be found at: > > > git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git > trace-fixes-v3.16-rc1 > > Tag SHA1: b6890d3b54aa3ff1aa34afb6c7af367895b9f07a > Head SHA1: 72fa1a896d8ef355e81270667803ceb16a3dd13f > > > Oleg Nesterov (3): > tracing: Fix syscall_*regfunc() vs copy_process() race > tracing: Change syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread() > tracing: syscall_regfunc() should not skip kernel threads > > ---- > include/trace/syscall.h | 15 +++++++++++++++ > kernel/fork.c | 2 ++ > kernel/tracepoint.c | 26 +++++++++++--------------- > 3 files changed, 28 insertions(+), 15 deletions(-) > --------------------------- > diff --git a/include/trace/syscall.h b/include/trace/syscall.h > index fed853f3d7aa..291c2824fafb 100644 > --- a/include/trace/syscall.h > +++ b/include/trace/syscall.h > @@ -4,6 +4,7 @@ > #include > #include > #include > +#include > > #include > > @@ -32,4 +33,18 @@ struct syscall_metadata { > struct ftrace_event_call *exit_event; > }; > > +#ifdef CONFIG_TRACEPOINTS > +static inline void syscall_tracepoint_update(struct task_struct *p) > +{ > + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) > + set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT); > + else > + clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT); > +} > +#else > +static inline void syscall_tracepoint_update(struct task_struct *p) > +{ > +} > +#endif > + > #endif /* _TRACE_SYSCALL_H */ > diff --git a/kernel/fork.c b/kernel/fork.c > index d2799d1fc952..6a13c46cd87d 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1487,7 +1487,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, > > total_forks++; > spin_unlock(¤t->sighand->siglock); > + syscall_tracepoint_update(p); > write_unlock_irq(&tasklist_lock); > + > proc_fork_connector(p); > cgroup_post_fork(p); > if (clone_flags & CLONE_THREAD) > diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c > index 33cbd8c203f8..3490407dc7b7 100644 > --- a/kernel/tracepoint.c > +++ b/kernel/tracepoint.c > @@ -492,33 +492,29 @@ static int sys_tracepoint_refcount; > > void syscall_regfunc(void) > { > - unsigned long flags; > - struct task_struct *g, *t; > + struct task_struct *p, *t; > > if (!sys_tracepoint_refcount) { > - read_lock_irqsave(&tasklist_lock, flags); > - do_each_thread(g, t) { > - /* Skip kernel threads. */ > - if (t->mm) > - set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); > - } while_each_thread(g, t); > - read_unlock_irqrestore(&tasklist_lock, flags); > + read_lock(&tasklist_lock); > + for_each_process_thread(p, t) { > + set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); > + } > + read_unlock(&tasklist_lock); > } > sys_tracepoint_refcount++; > } > > void syscall_unregfunc(void) > { > - unsigned long flags; > - struct task_struct *g, *t; > + struct task_struct *p, *t; > > sys_tracepoint_refcount--; > if (!sys_tracepoint_refcount) { > - read_lock_irqsave(&tasklist_lock, flags); > - do_each_thread(g, t) { > + read_lock(&tasklist_lock); > + for_each_process_thread(p, t) { > clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); > - } while_each_thread(g, t); > - read_unlock_irqrestore(&tasklist_lock, flags); > + } > + read_unlock(&tasklist_lock); > } > } > #endif