----- On May 5, 2020, at 9:16 AM, Thomas Gleixner t...@linutronix.de wrote:
> Make sure task_work runs before any kind of userspace -- very much > including signals -- is invoked. What is missing from this patch description is: _why_ is this deemed useful ? Also, color me confused: is "do_signal()" actually running any user-space, or just setting up the user-space stack for eventual return to signal handler ? Also, it might be OK, but we're changing the order of two things which have effects on each other: restartable sequences abort fixup for preemption and do_signal(), which also have effects on rseq abort. Because those two will cause the abort to trigger, I suspect changing the order might be OK, but we really need to think this through. Thanks, Mathieu > > Suggested-by: Andy Lutomirski <l...@kernel.org> > Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> > Signed-off-by: Thomas Gleixner <t...@linutronix.de> > --- > arch/x86/entry/common.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > --- a/arch/x86/entry/common.c > +++ b/arch/x86/entry/common.c > @@ -156,16 +156,16 @@ static void exit_to_usermode_loop(struct > if (cached_flags & _TIF_PATCH_PENDING) > klp_update_patch_state(current); > > - /* deal with pending signal delivery */ > - if (cached_flags & _TIF_SIGPENDING) > - do_signal(regs); > - > if (cached_flags & _TIF_NOTIFY_RESUME) { > clear_thread_flag(TIF_NOTIFY_RESUME); > tracehook_notify_resume(regs); > rseq_handle_notify_resume(NULL, regs); > } > > + /* deal with pending signal delivery */ > + if (cached_flags & _TIF_SIGPENDING) > + do_signal(regs); > + > if (cached_flags & _TIF_USER_RETURN_NOTIFY) > fire_user_return_notifiers(); -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com