Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 2384ea8..1f04234 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Provide access to virtual console memory.
- * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
+ * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
* /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
* [minor: N]
*
@@ -80,7 +80,7 @@
struct vcs_poll_data {
struct notifier_block notifier;
unsigned int cons_num;
- bool seen_last_update;
+ int event;
wait_queue_head_t waitq;
struct fasync_struct *fasync;
};
@@ -93,9 +93,18 @@
struct vcs_poll_data *poll =
container_of(nb, struct vcs_poll_data, notifier);
int currcons = poll->cons_num;
+ int fa_band;
- if (code != VT_UPDATE)
+ switch (code) {
+ case VT_UPDATE:
+ fa_band = POLL_PRI;
+ break;
+ case VT_DEALLOCATE:
+ fa_band = POLL_HUP;
+ break;
+ default:
return NOTIFY_DONE;
+ }
if (currcons == 0)
currcons = fg_console;
@@ -104,9 +113,9 @@
if (currcons != vc->vc_num)
return NOTIFY_DONE;
- poll->seen_last_update = false;
+ poll->event = code;
wake_up_interruptible(&poll->waitq);
- kill_fasync(&poll->fasync, SIGIO, POLL_IN);
+ kill_fasync(&poll->fasync, SIGIO, fa_band);
return NOTIFY_OK;
}
@@ -131,6 +140,15 @@
poll->cons_num = console(file_inode(file));
init_waitqueue_head(&poll->waitq);
poll->notifier.notifier_call = vcs_notifier;
+ /*
+ * In order not to lose any update event, we must pretend one might
+ * have occurred before we have a chance to register our notifier.
+ * This is also how user space has come to detect which kernels
+ * support POLLPRI on /dev/vcs* devices i.e. using poll() with
+ * POLLPRI and a zero timeout.
+ */
+ poll->event = VT_UPDATE;
+
if (register_vt_notifier(&poll->notifier) != 0) {
kfree(poll);
return NULL;
@@ -261,7 +279,7 @@
poll = file->private_data;
if (count && poll)
- poll->seen_last_update = true;
+ poll->event = 0;
read = 0;
ret = 0;
while (count) {
@@ -335,8 +353,9 @@
if (p < HEADER_SIZE) {
size_t tmp_count;
- con_buf0[0] = (char)vc->vc_rows;
- con_buf0[1] = (char)vc->vc_cols;
+ /* clamp header values if they don't fit */
+ con_buf0[0] = min(vc->vc_rows, 0xFFu);
+ con_buf0[1] = min(vc->vc_cols, 0xFFu);
getconsxy(vc, con_buf0 + 2);
con_buf_start += p;
@@ -615,12 +634,21 @@
vcs_poll(struct file *file, poll_table *wait)
{
struct vcs_poll_data *poll = vcs_poll_data_get(file);
- __poll_t ret = DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI;
+ __poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
if (poll) {
poll_wait(file, &poll->waitq, wait);
- if (poll->seen_last_update)
+ switch (poll->event) {
+ case VT_UPDATE:
+ ret = DEFAULT_POLLMASK|EPOLLPRI;
+ break;
+ case VT_DEALLOCATE:
+ ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
+ break;
+ case 0:
ret = DEFAULT_POLLMASK;
+ break;
+ }
}
return ret;
}