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
 25void speakup_clear_selection(void)
 26{
 27	console_lock();
 28	clear_selection();
 29	console_unlock();
 30}
 31
 32static void __speakup_set_selection(struct work_struct *work)
 33{
 34	struct speakup_selection_work *ssw =
 35		container_of(work, struct speakup_selection_work, work);
 36
 37	struct tty_struct *tty;
 38	struct tiocl_selection sel;
 39
 40	sel = ssw->sel;
 41
 42	/* this ensures we copy sel before releasing the lock below */
 43	rmb();
 44
 45	/* release the lock by setting tty of the struct to NULL */
 46	tty = xchg(&ssw->tty, NULL);
 47
 48	if (spk_sel_cons != vc_cons[fg_console].d) {
 49		spk_sel_cons = vc_cons[fg_console].d;
 50		pr_warn("Selection: mark console not the same as cut\n");
 51		goto unref;
 52	}
 53
 54	set_selection_kernel(&sel, tty);
 55
 56unref:
 57	tty_kref_put(tty);
 58}
 59
 60static struct speakup_selection_work speakup_sel_work = {
 61	.work = __WORK_INITIALIZER(speakup_sel_work.work,
 62				   __speakup_set_selection)
 63};
 64
 65int speakup_set_selection(struct tty_struct *tty)
 66{
 67	/* we get kref here first in order to avoid a subtle race when
 68	 * cancelling selection work. getting kref first establishes the
 69	 * invariant that if speakup_sel_work.tty is not NULL when
 70	 * speakup_cancel_selection() is called, it must be the case that a put
 71	 * kref is pending.
 72	 */
 73	tty_kref_get(tty);
 74	if (cmpxchg(&speakup_sel_work.tty, NULL, tty)) {
 75		tty_kref_put(tty);
 76		return -EBUSY;
 77	}
 78	/* now we have the 'lock' by setting tty member of
 79	 * speakup_selection_work. wmb() ensures that writes to
 80	 * speakup_sel_work don't happen before cmpxchg() above.
 81	 */
 82	wmb();
 83
 84	speakup_sel_work.sel.xs = spk_xs + 1;
 85	speakup_sel_work.sel.ys = spk_ys + 1;
 86	speakup_sel_work.sel.xe = spk_xe + 1;
 87	speakup_sel_work.sel.ye = spk_ye + 1;
 88	speakup_sel_work.sel.sel_mode = TIOCL_SELCHAR;
 89
 90	schedule_work_on(WORK_CPU_UNBOUND, &speakup_sel_work.work);
 91
 92	return 0;
 93}
 94
 95void speakup_cancel_selection(void)
 96{
 97	struct tty_struct *tty;
 98
 99	cancel_work_sync(&speakup_sel_work.work);
100	/* setting to null so that if work fails to run and we cancel it,
101	 * we can run it again without getting EBUSY forever from there on.
102	 * we need to use xchg here to avoid race with speakup_set_selection()
103	 */
104	tty = xchg(&speakup_sel_work.tty, NULL);
105	if (tty)
106		tty_kref_put(tty);
107}
108
109static void __speakup_paste_selection(struct work_struct *work)
110{
111	struct speakup_selection_work *ssw =
112		container_of(work, struct speakup_selection_work, work);
113	struct tty_struct *tty = xchg(&ssw->tty, NULL);
114
115	paste_selection(tty);
116	tty_kref_put(tty);
117}
118
119static struct speakup_selection_work speakup_paste_work = {
120	.work = __WORK_INITIALIZER(speakup_paste_work.work,
121				   __speakup_paste_selection)
122};
123
124int speakup_paste_selection(struct tty_struct *tty)
125{
126	tty_kref_get(tty);
127	if (cmpxchg(&speakup_paste_work.tty, NULL, tty)) {
128		tty_kref_put(tty);
129		return -EBUSY;
130	}
131
132	schedule_work_on(WORK_CPU_UNBOUND, &speakup_paste_work.work);
133	return 0;
134}
135
136void speakup_cancel_paste(void)
137{
138	struct tty_struct *tty;
139
140	cancel_work_sync(&speakup_paste_work.work);
141	tty = xchg(&speakup_paste_work.tty, NULL);
142	if (tty)
143		tty_kref_put(tty);
144}