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@xxxxxxxxxx> Reported-and-tested-by: Jarek Czekalski <jarekczek@xxxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- drivers/staging/speakup/main.c | 1 + drivers/staging/speakup/selection.c | 38 +++++++++++++++++++++++++++++++------ drivers/staging/speakup/speakup.h | 1 + 3 files changed, 34 insertions(+), 6 deletions(-) diff --git a/drivers/staging/speakup/main.c b/drivers/staging/speakup/main.c index 3b6e535..7de79d5 100644 --- a/drivers/staging/speakup/main.c +++ b/drivers/staging/speakup/main.c @@ -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; diff --git a/drivers/staging/speakup/selection.c b/drivers/staging/speakup/selection.c index f0fb003..f67941e 100644 --- a/drivers/staging/speakup/selection.c +++ b/drivers/staging/speakup/selection.c @@ -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); +} diff --git a/drivers/staging/speakup/speakup.h b/drivers/staging/speakup/speakup.h index a7bccee..898dce5 100644 --- a/drivers/staging/speakup/speakup.h +++ b/drivers/staging/speakup/speakup.h @@ -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); -- Ben Hutchings It is easier to change the specification to fit the program than vice versa.
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