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qemu-char: really fix behavior on can_read = 0 

I misread the glib manual, g_source_remove does not let you re-attach
the source later.  This behavior (called "blocking" the source in glib)
is present in glib's source code, but private and not available outside
glib; hence, we have to resort to re-creating the source every time.

In fact, g_source_remove and g_source_destroy are the same thing,
except g_source_destroy is O(1) while g_source_remove scans a potentially
very long list of GSources in the current main loop.  Ugh.  Better
use g_source_destroy explicitly, and leave "tags" to those dummies who
cannot track their pointers' lifetimes.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1365426195-12596-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Paolo Bonzini 2013-04-08 15:03:15 +02:00 committed by Anthony Liguori
parent b9a7cfee12
commit 1e885b2527
1 changed files with 13 additions and 4 deletions
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17
qemu-char.c
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@ -596,9 +596,11 @@ typedef struct IOWatchPoll
{ {
GSource parent; GSource parent;
GIOChannel *channel;
GSource *src; GSource *src;
IOCanReadHandler *fd_can_read; IOCanReadHandler *fd_can_read;
GSourceFunc fd_read;
void *opaque; void *opaque;
} IOWatchPoll; } IOWatchPoll;
@ -611,15 +613,19 @@ static gboolean io_watch_poll_prepare(GSource *source, gint *timeout_)
{ {
IOWatchPoll *iwp = io_watch_poll_from_source(source); IOWatchPoll *iwp = io_watch_poll_from_source(source);
bool now_active = iwp->fd_can_read(iwp->opaque) > 0; bool now_active = iwp->fd_can_read(iwp->opaque) > 0;
bool was_active = g_source_get_context(iwp->src) != NULL; bool was_active = iwp->src != NULL;
if (was_active == now_active) { if (was_active == now_active) {
return FALSE; return FALSE;
} }
if (now_active) { if (now_active) {
iwp->src = g_io_create_watch(iwp->channel, G_IO_IN | G_IO_ERR | G_IO_HUP);
g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL);
g_source_attach(iwp->src, NULL); g_source_attach(iwp->src, NULL);
} else { } else {
g_source_remove(g_source_get_id(iwp->src)); g_source_destroy(iwp->src);
g_source_unref(iwp->src);
iwp->src = NULL;
} }
return FALSE; return FALSE;
} }
@ -638,7 +644,9 @@ static gboolean io_watch_poll_dispatch(GSource *source, GSourceFunc callback,
static void io_watch_poll_finalize(GSource *source) static void io_watch_poll_finalize(GSource *source)
{ {
IOWatchPoll *iwp = io_watch_poll_from_source(source); IOWatchPoll *iwp = io_watch_poll_from_source(source);
g_source_destroy(iwp->src);
g_source_unref(iwp->src); g_source_unref(iwp->src);
iwp->src = NULL;
} }
static GSourceFuncs io_watch_poll_funcs = { static GSourceFuncs io_watch_poll_funcs = {
@ -659,8 +667,9 @@ static guint io_add_watch_poll(GIOChannel *channel,
iwp = (IOWatchPoll *) g_source_new(&io_watch_poll_funcs, sizeof(IOWatchPoll)); iwp = (IOWatchPoll *) g_source_new(&io_watch_poll_funcs, sizeof(IOWatchPoll));
iwp->fd_can_read = fd_can_read; iwp->fd_can_read = fd_can_read;
iwp->opaque = user_data; iwp->opaque = user_data;
iwp->src = g_io_create_watch(channel, G_IO_IN | G_IO_ERR | G_IO_HUP); iwp->channel = channel;
g_source_set_callback(iwp->src, (GSourceFunc)fd_read, user_data, NULL); iwp->fd_read = (GSourceFunc) fd_read;
iwp->src = NULL;
return g_source_attach(&iwp->parent, NULL); return g_source_attach(&iwp->parent, NULL);
} }