Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
---
qemu-char.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++----------
qemu-char.h | 9 ++++++
2 files changed, 85 insertions(+), 15 deletions(-)
diff --git a/qemu-char.c b/qemu-char.c
index 0e4a30c..9e40e04 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -139,13 +139,23 @@ void qemu_chr_generic_open(CharDriverState *s)
}
}
+static uint32_t char_queue_get_avail(CharQueue *q)
+{
+ return sizeof(q->ring) - (q->prod - q->cons);
+}
+
+static bool char_queue_get_empty(CharQueue *q)
+{
+ return (q->cons == q->prod);
+}
+
static size_t char_queue_write(CharQueue *q, const void *data, size_t size)
{
const uint8_t *ptr = data;
size_t i;
for (i = 0; i < size; i++) {
- if ((q->prod - q->cons) == sizeof(q->ring)) {
+ if (char_queue_get_avail(q) == 0) {
break;
}
@@ -162,7 +172,7 @@ static size_t char_queue_read(CharQueue *q, void *data,
size_t size)
size_t i;
for (i = 0; i < size; i++) {
- if (q->cons == q->prod) {
+ if (char_queue_get_empty(q)) {
break;
}
@@ -173,25 +183,17 @@ static size_t char_queue_read(CharQueue *q, void *data,
size_t size)
return i;
}
-static uint32_t char_queue_get_avail(CharQueue *q)
-{
- return sizeof(q->ring) - (q->prod - q->cons);
-}
-
static void qemu_chr_flush_fe_tx(CharDriverState *s)
{
uint8_t buf[MAX_CHAR_QUEUE_RING];
- int len, written_len;
+ int len;
/* Drain the queue into a flat buffer */
len = char_queue_read(&s->fe_tx, buf, sizeof(buf));
- written_len = s->chr_write(s, buf, len);
- if (written_len < len) {
- /* If the backend didn't accept the full write, queue the unwritten
- * data back in the queue. */
- char_queue_write(&s->fe_tx, &buf[written_len], len - written_len);
- }
+ s->chr_write(s, buf, len);
+
+ /* We drop unwritten data until we have backend flow control */
}
int qemu_chr_fe_write(CharDriverState *s, const uint8_t *buf, int len)
@@ -210,11 +212,43 @@ int qemu_chr_fe_read(CharDriverState *s, uint8_t *buf,
int len)
return char_queue_read(&s->be_tx, buf, len);
}
+void qemu_chr_fe_set_handlers(CharDriverState *s,
+ IOHandler *chr_read,
+ IOHandler *chr_write,
+ IOEventHandler *chr_event,
+ void *opaque)
+{
+ if (!opaque && !chr_read && !chr_write && !chr_event) {
+ /* chr driver being released. */
+ ++s->avail_connections;
+ }
+ s->fe_read = chr_read;
+ s->fe_write = chr_write;
+ s->chr_event = chr_event;
+ s->handler_opaque = opaque;
+
+ /* FIXME broken for mux */
+ if (s->chr_update_read_handler) {
+ s->chr_update_read_handler(s);
+ }
+
+ /* We're connecting to an already opened device, so let's make sure we
+ also get the open event */
+ if (s->opened) {
+ qemu_chr_generic_open(s);
+ }
+}
+
static void qemu_chr_flush_be_tx(CharDriverState *s)
{
uint8_t buf[MAX_CHAR_QUEUE_RING];
int len;
+ /* Don't invoke the polling handlers if we have edge handlers installed. */
+ if (s->fe_read || s->fe_write) {
+ return;
+ }
+
/* Only drain what the be can handle */
len = s->chr_can_read(s->handler_opaque);
if (len == 0) {
@@ -240,9 +274,21 @@ int qemu_chr_be_can_write(CharDriverState *s)
int qemu_chr_be_write(CharDriverState *s, uint8_t *buf, int len)
{
int ret;
+ bool is_empty;
+
+ is_empty = char_queue_get_empty(&s->be_tx);
ret = char_queue_write(&s->be_tx, buf, len);
+ /* If the queue was empty, and now it's not, trigger a read edge
+ * event. */
+ if ((s->fe_read || s->fe_write) &&
+ (is_empty && !char_queue_get_empty(&s->be_tx))) {
+ if (s->fe_read) {
+ s->fe_read(s->handler_opaque);
+ }
+ }
+
qemu_chr_flush_be_tx(s);
return ret;
@@ -250,7 +296,22 @@ int qemu_chr_be_write(CharDriverState *s, uint8_t *buf,
int len)
int qemu_chr_be_read(CharDriverState *s, uint8_t *buf, int len)
{
- return char_queue_read(&s->fe_tx, buf, len);
+ bool is_full;
+ int ret;
+
+ is_full = (char_queue_get_avail(&s->fe_tx) == 0);
+
+ ret = char_queue_read(&s->fe_tx, buf, len);
+
+ /* If the queue was full, and now it's not, trigger an write edge
+ * event. */
+ if (is_full && char_queue_get_avail(&s->fe_tx)) {
+ if (s->fe_write) {
+ s->fe_write(s->handler_opaque);
+ }
+ }
+
+ return ret;
}
int qemu_chr_ioctl(CharDriverState *s, int cmd, void *arg)
diff --git a/qemu-char.h b/qemu-char.h
index a75bd1c..84fd628 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -70,6 +70,8 @@ struct CharDriverState {
IOEventHandler *chr_event;
IOCanReadHandler *chr_can_read;
IOReadHandler *chr_read;
+ IOHandler *fe_read;
+ IOHandler *fe_write;
void *handler_opaque;
void (*chr_send_event)(struct CharDriverState *chr, int event);
void (*chr_close)(struct CharDriverState *chr);
@@ -108,6 +110,13 @@ void qemu_chr_add_handlers(CharDriverState *s,
IOReadHandler *fd_read,
IOEventHandler *fd_event,
void *opaque);
+
+void qemu_chr_fe_set_handlers(CharDriverState *s,
+ IOHandler *chr_read,
+ IOHandler *chr_write,
+ IOEventHandler *chr_event,
+ void *opaque);
+
int qemu_chr_ioctl(CharDriverState *s, int cmd, void *arg);
void qemu_chr_generic_open(CharDriverState *s);
int qemu_chr_be_can_write(CharDriverState *s);
--
1.7.4.1
