On Thu, 19 Jun 2014 17:51:08 +0200 Oleg Nesterov <[email protected]> wrote:
> Please tell me if I should another "[PATCH]" email or resend 2-3 as well. > Sorry for inconvenience. This is fine. I'm going to do what I seldom do and rebase my for-next branch with this one instead. But first I'll run this through my cross-compile tests. I should have done that the fist time :-/ -- Steve > > ------------------------------------------------------------------------------- > Subject: [PATCH] tracing: Fix syscall_*regfunc() vs copy_process() race > > 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/[email protected] > > Cc: [email protected] # 2.6.33 > Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints" > Acked-by: Frederic Weisbecker <[email protected]> > Signed-off-by: Oleg Nesterov <[email protected]> > --- > 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..9674145 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 cafea61..f7417f5 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1485,7 +1485,9 @@ 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
