From 293d2a0014a0e849477413f55aaa05f2743b2e04 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Tue, 16 Jul 2013 20:19:41 +0200 Subject: [PATCH] monitor: maintain at most one G_IO_OUT watch When monitor_flush() is invoked repeatedly outside the monitor_unblocked() callback, for example from tlb_info() -> ... -> print_pte(), several watches may be added for the same event. This is no problem per se because the extra monitor_unblocked() callbacks are harmless if mon->outbuf is empty, the watches will be removed gradually. However a big number of watches can grow "gpollfds" without limit in glib_pollfds_fill(), triggering a -1/EINVAL condition in g_poll(). Keep at most one such watch, by following the pattern observable in eg. commits c874ea97 and c3d6b96e. The change has no effect when monitor_unblocked() calls monitor_flush() (when the watch can either be removed or renewed 1-for-1), but non-callback contexts won't create an additional watch when the monitor already has one. Related RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=970047 Signed-off-by: Laszlo Ersek Reviewed-by: Amit Shah Reviewed-by: Anthony Liguori Message-id: 1373998781-29561-3-git-send-email-lersek@redhat.com Signed-off-by: Anthony Liguori --- monitor.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/monitor.c b/monitor.c index 99b6ed9060..6db2ba4d7a 100644 --- a/monitor.c +++ b/monitor.c @@ -189,6 +189,7 @@ struct Monitor { int suspend_cnt; bool skip_flush; QString *outbuf; + guint watch; ReadLineState *rs; MonitorControl *mc; CPUState *mon_cpu; @@ -263,7 +264,10 @@ int monitor_read_password(Monitor *mon, ReadLineFunc *readline_func, static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, void *opaque) { - monitor_flush(opaque); + Monitor *mon = opaque; + + mon->watch = 0; + monitor_flush(mon); return FALSE; } @@ -294,7 +298,10 @@ void monitor_flush(Monitor *mon) QDECREF(mon->outbuf); mon->outbuf = tmp; } - qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, monitor_unblocked, mon); + if (mon->watch == 0) { + mon->watch = qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, + monitor_unblocked, mon); + } } }