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authorLaszlo Ersek <lersek@redhat.com>2013-07-16 20:19:41 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2013-07-18 11:22:57 -0500
commit293d2a0014a0e849477413f55aaa05f2743b2e04 (patch)
treefe9d005b60aa177949eeb1e2756fe2bd5d1fab2c /monitor.c
parentac8c26f633b01bb32cdf347f9dbd5a80c6712925 (diff)
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 <lersek@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Message-id: 1373998781-29561-3-git-send-email-lersek@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'monitor.c')
-rw-r--r--monitor.c11
1 files 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);
+ }
}
}