Messages in this thread | | | Date | Tue, 15 Apr 2014 01:57:20 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v2 1/3] tracing: fix syscall_*regfunc() vs copy_process() race |
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On Sun, Apr 13, 2014 at 08:58:54PM +0200, Oleg Nesterov wrote: > 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. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> --- > include/trace/syscall.h | 15 +++++++++++++++ > kernel/fork.c | 2 ++ > 2 files changed, 17 insertions(+), 0 deletions(-) > > diff --git a/include/trace/syscall.h b/include/trace/syscall.h > index fed853f..291c282 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; > }; > > +#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 a17621c..2d55a47 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1484,7 +1484,9 @@ 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) > -- > 1.5.5.1 > >
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