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authorPaolo Bonzini <pbonzini@redhat.com>2013-04-19 17:32:07 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2013-04-22 08:52:20 -0500
commit85a67692d04e15a6b7d5a0e2b9d573d8bffbe108 (patch)
tree360f1f11fd3c5a4f589bd273aa51e7b0d1c81587 /qemu-char.c
parent910b63682ea72f34307b8797c4cc81a1f2a0c47f (diff)
qemu-char: simplify pty polling
There is no need to use a timer and pty_chr_read to detect a connected pty. It is simpler to just call g_poll periodically and check for POLLHUP. It is done once per second, and only if the pty is disconnected, so it is cheap enough. Tested with "-monitor pty" and "-serial mon:pty", both of which work correctly and do not freeze QEMU. (How to test ptys? "socat -,raw,echo=0 /dev/pts/4,raw"). Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1366385529-10329-3-git-send-email-pbonzini@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'qemu-char.c')
-rw-r--r--qemu-char.c41
1 files changed, 17 insertions, 24 deletions
diff --git a/qemu-char.c b/qemu-char.c
index 552a4988c8..d14888d609 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -1028,7 +1028,6 @@ typedef struct {
GIOChannel *fd;
guint fd_tag;
int connected;
- int polling;
int read_bytes;
guint timer_tag;
} PtyCharDriver;
@@ -1044,12 +1043,6 @@ static gboolean pty_chr_timer(gpointer opaque)
if (s->connected) {
goto out;
}
- if (s->polling) {
- /* If we arrive here without polling being cleared due
- * read returning -EIO, then we are (re-)connected */
- pty_chr_state(chr, 1);
- goto out;
- }
/* Next poll ... */
pty_chr_update_read_handler(chr);
@@ -1128,22 +1121,17 @@ static gboolean pty_chr_read(GIOChannel *chan, GIOCondition cond, void *opaque)
static void pty_chr_update_read_handler(CharDriverState *chr)
{
PtyCharDriver *s = chr->opaque;
+ GPollFD pfd;
- if (s->fd_tag) {
- g_source_remove(s->fd_tag);
+ pfd.fd = g_io_channel_unix_get_fd(s->fd);
+ pfd.events = G_IO_OUT;
+ pfd.revents = 0;
+ g_poll(&pfd, 1, 0);
+ if (pfd.revents & G_IO_HUP) {
+ pty_chr_state(chr, 0);
+ } else {
+ pty_chr_state(chr, 1);
}
-
- s->fd_tag = io_add_watch_poll(s->fd, pty_chr_read_poll, pty_chr_read, chr);
- s->polling = 1;
- /*
- * Short timeout here: just need wait long enougth that qemu makes
- * it through the poll loop once. When reconnected we want a
- * short timeout so we notice it almost instantly. Otherwise
- * read() gives us -EIO instantly, making pty_chr_state() reset the
- * timeout to the normal (much longer) poll interval before the
- * timer triggers.
- */
- pty_chr_rearm_timer(chr, 10);
}
static void pty_chr_state(CharDriverState *chr, int connected)
@@ -1156,15 +1144,20 @@ static void pty_chr_state(CharDriverState *chr, int connected)
s->fd_tag = 0;
}
s->connected = 0;
- s->polling = 0;
/* (re-)connect poll interval for idle guests: once per second.
* We check more frequently in case the guests sends data to
* the virtual device linked to our pty. */
pty_chr_rearm_timer(chr, 1000);
} else {
- if (!s->connected)
+ if (s->timer_tag) {
+ g_source_remove(s->timer_tag);
+ s->timer_tag = 0;
+ }
+ if (!s->connected) {
qemu_chr_be_generic_open(chr);
- s->connected = 1;
+ s->connected = 1;
+ s->fd_tag = io_add_watch_poll(s->fd, pty_chr_read_poll, pty_chr_read, chr);
+ }
}
}