Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux

[uclinux-h8/linux.git] / drivers / tty / tty_buffer.c

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 5a3fa89..a660ab1 100644 (file)
--- 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);