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path: root/drivers/tty/tty_buffer.c
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Diffstat (limited to 'drivers/tty/tty_buffer.c')
-rw-r--r--drivers/tty/tty_buffer.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 4cf263d7d..a660ab181 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -242,7 +242,10 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
atomic_inc(&buf->priority);
mutex_lock(&buf->lock);
- while ((next = buf->head->next) != NULL) {
+ /* paired w/ release in __tty_buffer_request_room; ensures there are
+ * no pending memory accesses to the freed buffer
+ */
+ while ((next = smp_load_acquire(&buf->head->next)) != NULL) {
tty_buffer_free(port, buf->head);
buf->head = next;
}
@@ -290,13 +293,15 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
if (n != NULL) {
n->flags = flags;
buf->tail = n;
- b->commit = b->used;
- /* paired w/ barrier in flush_to_ldisc(); ensures the
+ /* paired w/ acquire in flush_to_ldisc(); ensures
+ * flush_to_ldisc() sees buffer data.
+ */
+ smp_store_release(&b->commit, b->used);
+ /* paired w/ acquire in flush_to_ldisc(); ensures the
* latest commit value can be read before the head is
* advanced to the next buffer
*/
- smp_wmb();
- b->next = n;
+ smp_store_release(&b->next, n);
} else if (change)
size = 0;
else
@@ -394,7 +399,10 @@ void tty_schedule_flip(struct tty_port *port)
{
struct tty_bufhead *buf = &port->buf;
- buf->tail->commit = buf->tail->used;
+ /* paired w/ acquire in flush_to_ldisc(); ensures
+ * flush_to_ldisc() sees buffer data.
+ */
+ smp_store_release(&buf->tail->commit, buf->tail->used);
schedule_work(&buf->work);
}
EXPORT_SYMBOL(tty_schedule_flip);
@@ -445,7 +453,6 @@ receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
if (count)
disc->ops->receive_buf(tty, p, f, count);
}
- head->read += count;
return count;
}
@@ -469,7 +476,7 @@ static void flush_to_ldisc(struct work_struct *work)
struct tty_struct *tty;
struct tty_ldisc *disc;
- tty = port->itty;
+ tty = READ_ONCE(port->itty);
if (tty == NULL)
return;
@@ -488,13 +495,15 @@ static void flush_to_ldisc(struct work_struct *work)
if (atomic_read(&buf->priority))
break;
- next = head->next;
- /* paired w/ barrier in __tty_buffer_request_room();
+ /* paired w/ release in __tty_buffer_request_room();
* ensures commit value read is not stale if the head
* is advancing to the next buffer
*/
- smp_rmb();
- count = head->commit - head->read;
+ next = smp_load_acquire(&head->next);
+ /* paired w/ release in __tty_buffer_request_room() or in
+ * tty_buffer_flush(); ensures we see the committed buffer data
+ */
+ count = smp_load_acquire(&head->commit) - head->read;
if (!count) {
if (next == NULL) {
check_other_closed(tty);
@@ -508,6 +517,7 @@ static void flush_to_ldisc(struct work_struct *work)
count = receive_buf(tty, head, count);
if (!count)
break;
+ head->read += count;
}
mutex_unlock(&buf->lock);