From: Jan Lübbe <[EMAIL PROTECTED]>
The new behaviour of CFS exposes a race which occurs if a switch is
requested when vt_mode.mode is VT_PROCESS.
The process with vc->vt_pid is signaled before vc->vt_newvt is set. This
causes the switch to fail when triggered by the monitoing process
because the target is still -1.
Signed-off-by: Jan Lübbe <[EMAIL PROTECTED]>
---
Index: linux-2.6.22/drivers/char/vt_ioctl.c
===================================================================
--- linux-2.6.22.orig/drivers/char/vt_ioctl.c
+++ linux-2.6.22/drivers/char/vt_ioctl.c
@@ -1208,15 +1208,18 @@
/*
* Send the signal as privileged - kill_pid() will
* tell us if the process has gone or something else
- * is awry
+ * is awry.
+ *
+ * We need to set vt_newvt *before* sending the signal or we
+ * have a race.
*/
+ vc->vt_newvt = new_vc->vc_num;
if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
/*
* It worked. Mark the vt to switch to and
* return. The process needs to send us a
* VT_RELDISP ioctl to complete the switch.
*/
- vc->vt_newvt = new_vc->vc_num;
return;
}
-
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