Messages in this thread | | | Date | Fri, 20 Jun 2014 18:11:25 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [for-next][PATCH v2 1/3] tracing: Fix syscall_*regfunc() vs copy_process() race |
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On Fri, Jun 20, 2014 at 06:45:19AM -0400, Steven Rostedt wrote: > From: Oleg Nesterov <oleg@redhat.com> > > syscall_regfunc() and syscall_unregfunc() should set/clear > TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race > with copy_process() and miss the new child which was not added to > the process/thread lists yet. > > Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT > under tasklist. > > Link: http://lkml.kernel.org/p/20140413185854.GB20668@redhat.com > > Cc: stable@vger.kernel.org # 2.6.33 > Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints" > Acked-by: Frederic Weisbecker <fweisbec@gmail.com> > Signed-off-by: Oleg Nesterov <oleg@redhat.com> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> --- > include/trace/syscall.h | 15 +++++++++++++++ > kernel/fork.c | 2 ++ > 2 files changed, 17 insertions(+) > > diff --git a/include/trace/syscall.h b/include/trace/syscall.h > index fed853f3d7aa..9674145e2f6a 100644 > --- a/include/trace/syscall.h > +++ b/include/trace/syscall.h > @@ -4,6 +4,7 @@ > #include <linux/tracepoint.h> > #include <linux/unistd.h> > #include <linux/ftrace_event.h> > +#include <linux/thread_info.h> > > #include <asm/ptrace.h> > > @@ -32,4 +33,18 @@ struct syscall_metadata { > struct ftrace_event_call *exit_event; > }; > > +#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_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) > -- > 2.0.0 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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