uml: DEBUG_SHIRQ fixes

A couple more DEBUG_SHIRQ fixes.

The previous mconsole blocking fix exposed the lack of O_NONBLOCK on the
mconsole socket.

Also, winch_interrupt started crashing because it is called at irq free time
and it tries to dereference tty->driver_data, which has already been set to
NULL.

I added some error cleanup in mconsole_init while I was there.

Cc: "Karol Swietlicki" <magotari@gmail.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index fac058b49282..2c898c4d6b6a 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -774,9 +774,11 @@ static irqreturn_t winch_interrupt(int irq, void *data)
         tty = winch->tty;
         if (tty != NULL) {
                 line = tty->driver_data;
-                chan_window_size(&line->chan_list, &tty->winsize.ws_row,
-                                 &tty->winsize.ws_col);
-                kill_pgrp(tty->pgrp, SIGWINCH, 1);
+                if (line != NULL) {
+                        chan_window_size(&line->chan_list, &tty->winsize.ws_row,
+                                         &tty->winsize.ws_col);
+                        kill_pgrp(tty->pgrp, SIGWINCH, 1);
+                }
         }
  out:
         if (winch->fd != -1)