I just tested the empty line lockup is gone, but now speakup-r does
not work, actually in the file I had, after reading a number of lines
when I hit control, the cursor was actually at the end of the file.
Thanks for working on this one.
On Sat, 24 Jun 2017 05:06:45 -0400,
Okash Khawaja wrote:
>
> Hi,
>
> The lockup when running speakup-r at start of an empty line occurs
> because simulated key press is generated (using speakup_fake_down_arrow)
> from context of keyboard_notifier_call callback which is called in
> interrupt context. The simulated keypress leads to
> keybaord_notifier_call to be trigerred again from the same context
> leading to the lockup. The exact cause could be priority inversion where
> simulated keypress cannot be processed because there is a real keyboard
> interrupt already being processed (the one from which simulated keypress
> was triggered), hence causing a deadlock. Please share your thoughts on
> this. Here is the call chain.
>
> (speakup-r) --> keyboard_notifier_call --> speakup_key --> do_spkup -->
> read_all_doc --> get_sentence_buf [which returns -1 because of empty
> line] --> kbd_fakekey2(RA_DOWN_ARROW) --> speakup_fake_down_arrow
>
> The following patch resolves this by not simulating the keypress inside
> keyboard notifier callback but instead delegating it to cursor_timer. In
> the above chain, when get_sentence_buf returns -1, this patch starts
> timer and passes RA_DOWN_ARROW as argument. When timer handler runs and
> sees RA_DOWN_ARROW, it will then call kbd_fakekey2(RA_DOWN_ARROW) which
> will correctly simulate the keypress inside timer context. I've tested
> this succesfully.
>
> It's the first time I've worked on this side of the code so please
> review carefully :)
>
> Finally, I have updated the test repo on github so you can test from
> there.
>
> Thanks,
> Okash
>
> ---
> drivers/staging/speakup/main.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> --- a/drivers/staging/speakup/main.c
> +++ b/drivers/staging/speakup/main.c
> @@ -1408,7 +1408,8 @@ static void read_all_doc(struct vc_data
> cursor_track = read_all_mode;
> spk_reset_index_count(0);
> if (get_sentence_buf(vc, 0) == -1) {
> - kbd_fakekey2(vc, RA_DOWN_ARROW);
> + del_timer(&cursor_timer);
> + start_read_all_timer(vc, RA_DOWN_ARROW);
> } else {
> say_sentence_num(0, 0);
> synth_insert_next_index(0);
--
Your life is like a penny. You're going to lose it. The question is:
How do
you spend it?
John Covici
covici@xxxxxxxxxxxxxx
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