mieq: Backtrace when the queue overflows.

Since we're probably stuck down in a driver somewhere, let's at least
try to point out where.  This will need to be rethought when the input
thread work lands though.

1 files changed, 6 insertions, 0 deletions

diff --git a/mi/mieq.c b/mi/mieq.c
index 0a1b74028..062dede06 100644
--- a/mi/mieq.c
+++ b/mi/mieq.c
@@ -169,6 +169,7 @@ mieqEnqueue(DeviceIntPtr pDev, xEvent *e)
 	oldtail = (oldtail - 1) % QUEUE_SIZE;
     }
     else {
+	static int stuck = 0;
 	newtail = (oldtail + 1) % QUEUE_SIZE;
 	/* Toss events which come in late.  Usually this means your server's
          * stuck in an infinite loop somewhere, but SIGIO is still getting
@@ -176,8 +177,13 @@ mieqEnqueue(DeviceIntPtr pDev, xEvent *e)
 	if (newtail == miEventQueue.head) {
             ErrorF("[mi] EQ overflowing. The server is probably stuck "
                    "in an infinite loop.\n");
+	    if (!stuck) {
+		xorg_backtrace();
+		stuck = 1;
+	    }
 	    return;
         }
+	stuck = 0;
 	miEventQueue.tail = newtail;
     }