1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/slab.h> /* for kmalloc */
  3#include <linux/consolemap.h>
  4#include <linux/interrupt.h>
  5#include <linux/sched.h>
  6#include <linux/device.h> /* for dev_warn */
  7#include <linux/selection.h>
  8#include <linux/workqueue.h>
  9#include <linux/tty.h>
 10#include <linux/tty_flip.h>
 11#include <linux/atomic.h>
 12#include <linux/console.h>
 13
 14#include "speakup.h"
 15
 16unsigned short spk_xs, spk_ys, spk_xe, spk_ye; /* our region points */
 17struct vc_data *spk_sel_cons;
 18
 19struct speakup_selection_work {
 20	struct work_struct work;
 21	struct tiocl_selection sel;
 22	struct tty_struct *tty;
 23};
 24
 25static void __speakup_set_selection(struct work_struct *work)
 26{
 27	struct speakup_selection_work *ssw =
 28		container_of(work, struct speakup_selection_work, work);
 29
 30	struct tty_struct *tty;
 31	struct tiocl_selection sel;
 32
 33	sel = ssw->sel;
 34
 35	/* this ensures we copy sel before releasing the lock below */
 36	rmb();
 37
 38	/* release the lock by setting tty of the struct to NULL */
 39	tty = xchg(&ssw->tty, NULL);
 40
 41	if (spk_sel_cons != vc_cons[fg_console].d) {
 42		spk_sel_cons = vc_cons[fg_console].d;
 43		pr_warn("Selection: mark console not the same as cut\n");
 44		goto unref;
 45	}
 46
 47	console_lock();
 48	clear_selection();
 49	console_unlock();
 50
 51	set_selection_kernel(&sel, tty);
 52
 53unref:
 54	tty_kref_put(tty);
 55}
 56
 57static struct speakup_selection_work speakup_sel_work = {
 58	.work = __WORK_INITIALIZER(speakup_sel_work.work,
 59				   __speakup_set_selection)
 60};
 61
 62int speakup_set_selection(struct tty_struct *tty)
 63{
 64	/* we get kref here first in order to avoid a subtle race when
 65	 * cancelling selection work. getting kref first establishes the
 66	 * invariant that if speakup_sel_work.tty is not NULL when
 67	 * speakup_cancel_selection() is called, it must be the case that a put
 68	 * kref is pending.
 69	 */
 70	tty_kref_get(tty);
 71	if (cmpxchg(&speakup_sel_work.tty, NULL, tty)) {
 72		tty_kref_put(tty);
 73		return -EBUSY;
 74	}
 75	/* now we have the 'lock' by setting tty member of
 76	 * speakup_selection_work. wmb() ensures that writes to
 77	 * speakup_sel_work don't happen before cmpxchg() above.
 78	 */
 79	wmb();
 80
 81	speakup_sel_work.sel.xs = spk_xs + 1;
 82	speakup_sel_work.sel.ys = spk_ys + 1;
 83	speakup_sel_work.sel.xe = spk_xe + 1;
 84	speakup_sel_work.sel.ye = spk_ye + 1;
 85	speakup_sel_work.sel.sel_mode = TIOCL_SELCHAR;
 86
 87	schedule_work_on(WORK_CPU_UNBOUND, &speakup_sel_work.work);
 88
 89	return 0;
 90}
 91
 92void speakup_cancel_selection(void)
 93{
 94	struct tty_struct *tty;
 95
 96	cancel_work_sync(&speakup_sel_work.work);
 97	/* setting to null so that if work fails to run and we cancel it,
 98	 * we can run it again without getting EBUSY forever from there on.
 99	 * we need to use xchg here to avoid race with speakup_set_selection()
100	 */
101	tty = xchg(&speakup_sel_work.tty, NULL);
102	if (tty)
103		tty_kref_put(tty);
104}
105
106static void __speakup_paste_selection(struct work_struct *work)
107{
108	struct speakup_selection_work *ssw =
109		container_of(work, struct speakup_selection_work, work);
110	struct tty_struct *tty = xchg(&ssw->tty, NULL);
111
112	paste_selection(tty);
113	tty_kref_put(tty);
114}
115
116static struct speakup_selection_work speakup_paste_work = {
117	.work = __WORK_INITIALIZER(speakup_paste_work.work,
118				   __speakup_paste_selection)
119};
120
121int speakup_paste_selection(struct tty_struct *tty)
122{
123	tty_kref_get(tty);
124	if (cmpxchg(&speakup_paste_work.tty, NULL, tty)) {
125		tty_kref_put(tty);
126		return -EBUSY;
127	}
128
129	schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
130	return 0;
131}
132
133void speakup_cancel_paste(void)
134{
135	struct tty_struct *tty;
136
137	cancel_work_sync(&speakup_paste_work.work);
138	tty = xchg(&speakup_paste_work.tty, NULL);
139	if (tty)
140		tty_kref_put(tty);
141}