Staging: speakup: Move pasting into a work item

Input is handled in softirq context, but when pasting we may
need to sleep.  speakup_paste_selection() currently tries to
bodge this by busy-waiting if in_atomic(), but that doesn't
help because the ldisc may also sleep.

For bonus breakage, speakup_paste_selection() changes the
state of current, even though it's not running in process
context.

Move it into a work item and make sure to cancel it on exit.

References: https://bugs.debian.org/735202
References: https://bugs.debian.org/744015
Reported-by: Paul Gevers <elbrus@debian.org>
Reported-and-tested-by: Jarek Czekalski <jarekczek@poczta.onet.pl>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ben Hutchings 2014-05-19 00:56:22 +01:00 committed by Greg Kroah-Hartman
parent ffed54dced
commit d750013580
3 changed files with 34 additions and 6 deletions

View File

@ -2218,6 +2218,7 @@ static void __exit speakup_exit(void)
unregister_keyboard_notifier(&keyboard_notifier_block);
unregister_vt_notifier(&vt_notifier_block);
speakup_unregister_devsynth();
speakup_cancel_paste();
del_timer(&cursor_timer);
kthread_stop(speakup_task);
speakup_task = NULL;

View File

@ -4,6 +4,8 @@
#include <linux/sched.h>
#include <linux/device.h> /* for dev_warn */
#include <linux/selection.h>
#include <linux/workqueue.h>
#include <asm/cmpxchg.h>
#include "speakup.h"
@ -121,20 +123,24 @@ int speakup_set_selection(struct tty_struct *tty)
return 0;
}
/* TODO: move to some helper thread, probably. That'd fix having to check for
* in_atomic(). */
int speakup_paste_selection(struct tty_struct *tty)
struct speakup_paste_work {
struct work_struct work;
struct tty_struct *tty;
};
static void __speakup_paste_selection(struct work_struct *work)
{
struct speakup_paste_work *spw =
container_of(work, struct speakup_paste_work, work);
struct tty_struct *tty = xchg(&spw->tty, NULL);
struct vc_data *vc = (struct vc_data *) tty->driver_data;
int pasted = 0, count;
DECLARE_WAITQUEUE(wait, current);
add_wait_queue(&vc->paste_wait, &wait);
while (sel_buffer && sel_buffer_lth > pasted) {
set_current_state(TASK_INTERRUPTIBLE);
if (test_bit(TTY_THROTTLED, &tty->flags)) {
if (in_atomic())
/* if we are in an interrupt handler, abort */
break;
schedule();
continue;
}
@ -146,6 +152,26 @@ int speakup_paste_selection(struct tty_struct *tty)
}
remove_wait_queue(&vc->paste_wait, &wait);
current->state = TASK_RUNNING;
tty_kref_put(tty);
}
static struct speakup_paste_work speakup_paste_work = {
.work = __WORK_INITIALIZER(speakup_paste_work.work,
__speakup_paste_selection)
};
int speakup_paste_selection(struct tty_struct *tty)
{
if (cmpxchg(&speakup_paste_work.tty, NULL, tty) != NULL)
return -EBUSY;
tty_kref_get(tty);
schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
return 0;
}
void speakup_cancel_paste(void)
{
cancel_work_sync(&speakup_paste_work.work);
tty_kref_put(speakup_paste_work.tty);
}

View File

@ -75,6 +75,7 @@ extern void synth_buffer_clear(void);
extern void speakup_clear_selection(void);
extern int speakup_set_selection(struct tty_struct *tty);
extern int speakup_paste_selection(struct tty_struct *tty);
extern void speakup_cancel_paste(void);
extern void speakup_register_devsynth(void);
extern void speakup_unregister_devsynth(void);
extern void synth_write(const char *buf, size_t count);