Prevent an O_NDELAY writer from blocking when a tty write is blocked by the tty atomic writer mutex
Without this a tty write could block if a previous blocking tty write was
in progress on the same tty and blocked by a line discipline or hardware
event. Originally found and reported by Dave Johnson.
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index fd471cb..918e24c 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -667,7 +667,7 @@
return 0;
}
- if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ if (tty_write_lock(tty, 0) < 0)
return -ERESTARTSYS;
if (was_stopped)
@@ -675,7 +675,7 @@
tty->driver->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
- mutex_unlock(&tty->atomic_write_lock);
+ tty_write_unlock(tty);
return 0;
}