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[Qemu-devel] [PATCH 2/3] qemu-char: simplify pty polling
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 2/3] qemu-char: simplify pty polling |
Date: |
Tue, 16 Apr 2013 13:10:41 +0200 |
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 <address@hidden>
---
qemu-char.c | 41 +++++++++++++++++------------------------
1 file changed, 17 insertions(+), 24 deletions(-)
diff --git a/qemu-char.c b/qemu-char.c
index 552a498..d14888d 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);
+ }
}
}
--
1.8.1.4
- [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Paolo Bonzini, 2013/04/16
- [Qemu-devel] [PATCH 1/3] qemu-char: use consistent idiom for removing sources, Paolo Bonzini, 2013/04/16
- [Qemu-devel] [PATCH 3/3] qemu-char: correct return value from chr_read functions, Paolo Bonzini, 2013/04/16
- [Qemu-devel] [PATCH 2/3] qemu-char: simplify pty polling,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Gerd Hoffmann, 2013/04/16
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Gerd Hoffmann, 2013/04/17
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Paolo Bonzini, 2013/04/17
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Paolo Bonzini, 2013/04/17
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Gerd Hoffmann, 2013/04/18
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Paolo Bonzini, 2013/04/18
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Gerd Hoffmann, 2013/04/18
- Re: [Qemu-devel] [PATCH 0/3] another round of qemu-char fixes, Paolo Bonzini, 2013/04/18