2012-12-16 23:27:22 +00:00
|
|
|
From d06d51e96773ab8295e31f666466fb2edb093aa0 Mon Sep 17 00:00:00 2001
|
2012-01-13 19:46:23 +00:00
|
|
|
From: Amit Shah <amit.shah@redhat.com>
|
|
|
|
Date: Mon, 21 Mar 2011 22:05:10 +0100
|
2012-10-28 18:05:07 +00:00
|
|
|
Subject: [PATCH] char: Throttle when host connection is down#
|
2012-01-13 19:46:23 +00:00
|
|
|
|
|
|
|
When the host-side connection goes down, throttle the virtio-serial bus
|
|
|
|
and later unthrottle when a connection gets established. This helps
|
|
|
|
prevent any lost IO (guest->host) while the host connection was down.
|
|
|
|
|
|
|
|
Bugzilla: 621484
|
|
|
|
|
|
|
|
This commit actually helps the bug mentioned above as no writes will now
|
|
|
|
get lost because of the throttling done here. With just the patches
|
|
|
|
sent earlier for that bug, one write will end up getting lost in the
|
|
|
|
worst case (host d/c, guest write, host connect).
|
|
|
|
|
|
|
|
Signed-off-by: Amit Shah <amit.shah@redhat.com>
|
2012-08-28 15:15:48 +00:00
|
|
|
Signed-off-by: Cole Robinson <crobinso@redhat.com>
|
2012-01-13 19:46:23 +00:00
|
|
|
---
|
2012-08-06 19:53:39 +00:00
|
|
|
qemu-char.c | 14 ++++++++++++++
|
2012-07-05 09:22:23 +00:00
|
|
|
1 file changed, 14 insertions(+)
|
2012-01-13 19:46:23 +00:00
|
|
|
|
|
|
|
diff --git a/qemu-char.c b/qemu-char.c
|
2012-10-28 18:05:07 +00:00
|
|
|
index 9f8608a..bfc94a5 100644
|
2012-01-13 19:46:23 +00:00
|
|
|
--- a/qemu-char.c
|
|
|
|
+++ b/qemu-char.c
|
|
|
|
@@ -140,6 +140,9 @@ static void qemu_chr_generic_open_bh(void *opaque)
|
|
|
|
{
|
|
|
|
CharDriverState *s = opaque;
|
|
|
|
qemu_chr_be_event(s, CHR_EVENT_OPENED);
|
|
|
|
+ if (s->write_blocked) {
|
|
|
|
+ char_write_unblocked(s);
|
|
|
|
+ }
|
|
|
|
qemu_bh_delete(s->bh);
|
|
|
|
s->bh = NULL;
|
|
|
|
}
|
2012-10-28 18:05:07 +00:00
|
|
|
@@ -2244,6 +2247,17 @@ static int tcp_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
|
2012-01-13 19:46:23 +00:00
|
|
|
ret = send_all(chr, s->fd, buf, len);
|
|
|
|
if (ret == -1 && errno == EPIPE) {
|
|
|
|
tcp_closed(chr);
|
|
|
|
+
|
|
|
|
+ if (chr->chr_enable_write_fd_handler && chr->chr_write_unblocked) {
|
|
|
|
+ /*
|
|
|
|
+ * Since we haven't written out anything, let's say
|
|
|
|
+ * we're throttled. This will prevent any output from
|
|
|
|
+ * the guest getting lost if host-side chardev goes
|
|
|
|
+ * down. Unthrottle when we re-connect.
|
|
|
|
+ */
|
|
|
|
+ chr->write_blocked = true;
|
|
|
|
+ return 0;
|
|
|
|
+ }
|
|
|
|
}
|
|
|
|
return ret;
|
|
|
|
} else {
|