The new patch seems to work fine, after limited testing. Thanks.
On Tue, 03 Nov 2020 15:45:26 -0500,
Samuel Thibault wrote:
>
> [1 <text/plain; us-ascii (7bit)>]
> John Covici, le mar. 03 nov. 2020 14:21:10 -0500, a ecrit:
> > I am sorry to report that your patch does not work, probably because
> > it references drivers/accessibility rather than staging. If that is
> > the case, I could change it and try again, or let me know.
>
> Ah, yes, sorry, that should rather be staging, here is a fixed patch.
>
> Samuel
> [2 speakup_in_nowait <text/plain; us-ascii (7bit)>]
> speakup ttyio: Do not schedule() in ttyio_in_nowait
>
> With the ltlk and spkout drivers, the index read function, i.e.
> in_nowait, is getting called from the read_all_doc mechanism, from
> the timer softirq:
>
> Call Trace:
> <IRQ>
> dump_stack+0x71/0x98
> dequeue_task_idle+0x1f/0x28
> __schedule+0x167/0x5d6
> ? trace_hardirqs_on+0x2e/0x3a
> ? usleep_range+0x7f/0x7f
> schedule+0x8a/0xae
> schedule_timeout+0xb1/0xea
> ? del_timer_sync+0x31/0x31
> do_wait_for_common+0xba/0x12b
> ? wake_up_q+0x45/0x45
> wait_for_common+0x37/0x50
> ttyio_in+0x2a/0x6b
> spk_ttyio_in_nowait+0xc/0x13
> spk_get_index_count+0x20/0x93
> cursor_done+0x1c6/0x4c6
> ? read_all_doc+0xb1/0xb1
> call_timer_fn+0x89/0x140
> run_timer_softirq+0x164/0x1a5
> ? read_all_doc+0xb1/0xb1
> ? hrtimer_forward+0x7b/0x87
> ? timerqueue_add+0x62/0x68
> ? enqueue_hrtimer+0x95/0x9f
> __do_softirq+0x181/0x31f
> irq_exit+0x6a/0x86
> smp_apic_timer_interrupt+0x15e/0x183
> apic_timer_interrupt+0xf/0x20
> </IRQ>
>
> We thus should not schedule() at all, even with timeout == 0, this
> crashes the kernel. We can however use try_wait_for_completion()
> instead of wait_for_completion_timeout(0).
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> Reported-by: John Covici <covici@xxxxxxxxxxxxxx>
> TODO Tested-by: John Covici <covici@xxxxxxxxxxxxxx>
>
> ---
> drivers/staging/speakup/spk_ttyio.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> --- a/drivers/staging/speakup/spk_ttyio.c
> +++ b/drivers/staging/speakup/spk_ttyio.c
> @@ -298,11 +298,13 @@ static unsigned char ttyio_in(int timeou
> struct spk_ldisc_data *ldisc_data = speakup_tty->disc_data;
> char rv;
>
> - if (wait_for_completion_timeout(&ldisc_data->completion,
> + if (!timeout) {
> + if (!try_wait_for_completion(&ldisc_data->completion))
> + return 0xff;
> + } else if (wait_for_completion_timeout(&ldisc_data->completion,
> usecs_to_jiffies(timeout)) == 0) {
> - if (timeout)
> - pr_warn("spk_ttyio: timeout (%d) while waiting for input\n",
> - timeout);
> + pr_warn("spk_ttyio: timeout (%d) while waiting for input\n",
> + timeout);
> return 0xff;
> }
>
--
Your life is like a penny. You're going to lose it. The question is:
How do
you spend it?
John Covici wb2una
covici@xxxxxxxxxxxxxx
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