releases/3.14.7/staging-speakup-move-pasting-into-a-work-item.patch

   1 From d7500135802ca55b3f4e01a16544e8b34082f8c3 Mon Sep 17 00:00:00 2001
   2 From: Ben Hutchings <ben@decadent.org.uk>
   3 Date: Mon, 19 May 2014 00:56:22 +0100
   4 Subject: Staging: speakup: Move pasting into a work item
   5
   6 From: Ben Hutchings <ben@decadent.org.uk>
   7
   8 commit d7500135802ca55b3f4e01a16544e8b34082f8c3 upstream.
   9
  10 Input is handled in softirq context, but when pasting we may
  11 need to sleep.  speakup_paste_selection() currently tries to
  12 bodge this by busy-waiting if in_atomic(), but that doesn't
  13 help because the ldisc may also sleep.
  14
  15 For bonus breakage, speakup_paste_selection() changes the
  16 state of current, even though it's not running in process
  17 context.
  18
  19 Move it into a work item and make sure to cancel it on exit.
  20
  21 References: https://bugs.debian.org/735202
  22 References: https://bugs.debian.org/744015
  23 Reported-by: Paul Gevers <elbrus@debian.org>
  24 Reported-and-tested-by: Jarek Czekalski <jarekczek@poczta.onet.pl>
  25 Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
  26 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  27
  28 ---
  29  drivers/staging/speakup/main.c      |    1
  30  drivers/staging/speakup/selection.c |   40 +++++++++++++++++++++++++++++-------
  31  drivers/staging/speakup/speakup.h   |    1
  32  3 files changed, 35 insertions(+), 7 deletions(-)
  33
  34 --- a/drivers/staging/speakup/main.c
  35 +++ b/drivers/staging/speakup/main.c
  36 @@ -2218,6 +2218,7 @@ static void __exit speakup_exit(void)
  37         unregister_keyboard_notifier(&keyboard_notifier_block);
  38         unregister_vt_notifier(&vt_notifier_block);
  39         speakup_unregister_devsynth();
  40 +       speakup_cancel_paste();
  41         del_timer(&cursor_timer);
  42         kthread_stop(speakup_task);
  43         speakup_task = NULL;
  44 --- a/drivers/staging/speakup/selection.c
  45 +++ b/drivers/staging/speakup/selection.c
  46 @@ -4,6 +4,8 @@
  47  #include <linux/sched.h>
  48  #include <linux/device.h> /* for dev_warn */
  49  #include <linux/selection.h>
  50 +#include <linux/workqueue.h>
  51 +#include <asm/cmpxchg.h>
  52
  53  #include "speakup.h"
  54
  55 @@ -121,20 +123,24 @@ int speakup_set_selection(struct tty_str
  56         return 0;
  57  }
  58
  59 -/* TODO: move to some helper thread, probably.  That'd fix having to check for
  60 - * in_atomic().  */
  61 -int speakup_paste_selection(struct tty_struct *tty)
  62 -{
  63 +struct speakup_paste_work {
  64 +       struct work_struct work;
  65 +       struct tty_struct *tty;
  66 +};
  67 +
  68 +static void __speakup_paste_selection(struct work_struct *work)
  69 +{
  70 +       struct speakup_paste_work *spw =
  71 +               container_of(work, struct speakup_paste_work, work);
  72 +       struct tty_struct *tty = xchg(&spw->tty, NULL);
  73         struct vc_data *vc = (struct vc_data *) tty->driver_data;
  74         int pasted = 0, count;
  75         DECLARE_WAITQUEUE(wait, current);
  76 +
  77         add_wait_queue(&vc->paste_wait, &wait);
  78         while (sel_buffer && sel_buffer_lth > pasted) {
  79                 set_current_state(TASK_INTERRUPTIBLE);
  80                 if (test_bit(TTY_THROTTLED, &tty->flags)) {
  81 -                       if (in_atomic())
  82 -                               /* if we are in an interrupt handler, abort */
  83 -                               break;
  84                         schedule();
  85                         continue;
  86                 }
  87 @@ -146,6 +152,26 @@ int speakup_paste_selection(struct tty_s
  88         }
  89         remove_wait_queue(&vc->paste_wait, &wait);
  90         current->state = TASK_RUNNING;
  91 +       tty_kref_put(tty);
  92 +}
  93 +
  94 +static struct speakup_paste_work speakup_paste_work = {
  95 +       .work = __WORK_INITIALIZER(speakup_paste_work.work,
  96 +                                  __speakup_paste_selection)
  97 +};
  98 +
  99 +int speakup_paste_selection(struct tty_struct *tty)
 100 +{
 101 +       if (cmpxchg(&speakup_paste_work.tty, NULL, tty) != NULL)
 102 +               return -EBUSY;
 103 +
 104 +       tty_kref_get(tty);
 105 +       schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
 106         return 0;
 107  }
 108
 109 +void speakup_cancel_paste(void)
 110 +{
 111 +       cancel_work_sync(&speakup_paste_work.work);
 112 +       tty_kref_put(speakup_paste_work.tty);
 113 +}
 114 --- a/drivers/staging/speakup/speakup.h
 115 +++ b/drivers/staging/speakup/speakup.h
 116 @@ -77,6 +77,7 @@ extern void synth_buffer_clear(void);
 117  extern void speakup_clear_selection(void);
 118  extern int speakup_set_selection(struct tty_struct *tty);
 119  extern int speakup_paste_selection(struct tty_struct *tty);
 120 +extern void speakup_cancel_paste(void);
 121  extern void speakup_register_devsynth(void);
 122  extern void speakup_unregister_devsynth(void);
 123  extern void synth_write(const char *buf, size_t count);