Messages in this thread Patch in this message | | | Date | Thu, 15 Mar 2007 15:10:23 +0100 | From | Michal Januszewski <> | Subject | [PATCH] vt: fix a potential race in the VT_WAITACTIVE handler |
| |
On a multiprocessor machine the VT_WAITACTIVE ioctl call may return 0 if fg_console has already been updated in redraw_screen(), but the console switch itself hasn't been completed. Fix this by checking fg_console in vt_waitactive() with the console sem held.
Signed-off-by: Michal Januszewski <spock@gentoo.org>
--- diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c index 3a5d301..00b5b34 100644 --- a/drivers/char/vt_ioctl.c +++ b/drivers/char/vt_ioctl.c @@ -1041,8 +1041,12 @@ int vt_waitactive(int vt) for (;;) { set_current_state(TASK_INTERRUPTIBLE); retval = 0; - if (vt == fg_console) + acquire_console_sem(); + if (vt == fg_console) { + release_console_sem(); break; + } + release_console_sem(); retval = -EINTR; if (signal_pending(current)) break; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |