1 files changed, 17 insertions, 5 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 5a3fa8913880..a660ab181cca 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;
         }
@@ -290,7 +293,10 @@ 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/ 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
@@ -393,7 +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);
@@ -467,7 +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;
 
@@ -491,7 +500,10 @@ static void flush_to_ldisc(struct work_struct *work)
                  * is advancing to the next buffer
                  */
                 next = smp_load_acquire(&head->next);
-                count = head->commit - head->read;
+                /* 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);