> On May 28, 2019, at 2:12 AM, David Laight <David.Laight@xxxxxxxxxx> wrote:
>
> From: Deepa Dinamani
>> Sent: 24 May 2019 18:02
> ...
>> Look at the code before 854a6ed56839a:
>>
>> /*
>> * If we changed the signal mask, we need to restore the original one.
>> * In case we've got a signal while waiting, we do not restore the
>> * signal mask yet, and we allow do_signal() to deliver the signal on
>> * the way back to userspace, before the signal mask is restored.
>> */
>> if (sigmask) {
>> ####### This err has not been changed since ep_poll()
>> ####### So if there is a signal before this point, but
>> err = 0, then we goto else.
>> if (err == -EINTR) {
>> memcpy(¤t->saved_sigmask, &sigsaved,
>> sizeof(sigsaved));
>> set_restore_sigmask();
>> } else
>> ############ This is a problem if there is signal
>> pending that is sigmask should block.
>> ########### This is the whole reason we have
>> current->saved_sigmask?
>> set_current_blocked(&sigsaved);
>> }
>
> What happens if all that crap is just deleted (I presume from the
> bottom of ep_wait()) ?
Hmm, you have to update the saved_sigmask or the sigmask.
> I'm guessing that on the way back to userspace signal handlers for
> signals enabled in the process's current mask (the one specified
> to epoll_pwait) get called.
> Then the signal mask is loaded from current->saved_sigmask and
> and enabled signal handlers are called again.
Who is saving this saved_sigmask that is being restored on the way back?
> No special code there that depends on the syscall result, errno
> of the syscall number.
I didn’t say this has anything to do with errno.
-Deepa
