From 3a3567d337d3ee6fb2e2fcc1d27cd045ed97ae9b Mon Sep 17 00:00:00 2001 From: James Hogan Date: Thu, 8 Aug 2013 12:09:38 +0100 Subject: qemu-char: fix infinite recursion connecting to monitor pty Since commit bd5c51e (qemu-char: don't issue CHR_EVENT_OPEN in a BH), an infinite recursion occurs when putting the monitor on a pty (-monitor pty) and connecting a terminal to the slave port. This is because of the qemu_chr_be_event(s, CHR_EVENT_OPENED) added to qemu_chr_be_generic_open(). This event is captured by monitor_event() which prints a welcome message to the character device. The flush of that welcome message retriggers another open event in pty_chr_state() because it checks s->connected, but only sets it to 1 after calling qemu_chr_be_generic_open(). I've fixed this by setting s->connected = 1 before the call to qemu_chr_be_generic_open() instead of after, so that the recursive pty_chr_state() doesn't call it again. An example snippet of repeating backtrace: ... #107486 0x007aec58 in monitor_flush (mon=0xf418b0) at qemu/monitor.c:288 #107487 0x007aee7c in monitor_puts (mon=0xf418b0, str=0x1176d07 "") at qemu/monitor.c:322 #107488 0x007aef20 in monitor_vprintf (mon=0xf418b0, fmt=0x8d4820 "QEMU %s monitor - type 'help' for more information\n", ap=0x7f432be0) at qemu/monitor.c:339 #107489 0x007aefac in monitor_printf (mon=0xf418b0, fmt=0x8d4820 "QEMU %s monitor - type 'help' for more information\n") at qemu/monitor.c:347 #107490 0x007ba4bc in monitor_event (opaque=0xf418b0, event=2) at qemu/monitor.c:4699 #107491 0x00684c28 in qemu_chr_be_event (s=0xf37788, event=2) at qemu/qemu-char.c:108 #107492 0x00684c70 in qemu_chr_be_generic_open (s=0xf37788) at qemu/qemu-char.c:113 #107493 0x006880a4 in pty_chr_state (chr=0xf37788, connected=1) at qemu/qemu-char.c:1145 #107494 0x00687fa4 in pty_chr_update_read_handler (chr=0xf37788) at qemu/qemu-char.c:1121 #107495 0x00687c9c in pty_chr_write (chr=0xf37788, buf=0x70b3c008
, len=538720) at qemu/qemu-char.c:1063 #107496 0x00684cc4 in qemu_chr_fe_write (s=0xf37788, buf=0x70b3c008
, len=538720) at qemu/qemu-char.c:118 ... Signed-off-by: James Hogan Tested-by: Michael Roth Message-id: 1375960178-10882-1-git-send-email-james.hogan@imgtec.com Cc: Michael Roth Cc: Anthony Liguori Signed-off-by: Anthony Liguori --- qemu-char.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'qemu-char.c') diff --git a/qemu-char.c b/qemu-char.c index 16f3ad77de..1be1cf676e 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -1142,8 +1142,8 @@ static void pty_chr_state(CharDriverState *chr, int connected) s->timer_tag = 0; } if (!s->connected) { - qemu_chr_be_generic_open(chr); s->connected = 1; + qemu_chr_be_generic_open(chr); s->fd_tag = io_add_watch_poll(s->fd, pty_chr_read_poll, pty_chr_read, chr); } } -- cgit v1.2.1