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authorAlan Cox <alan@llwyncelyn.cymru>2017-06-02 15:49:30 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-03 12:43:46 +0300
commit8a8dabf2dd68caff842d38057097c23bc514ea6e (patch)
tree98e019474882e4f4ea47ac77e162c86f3540c726 /drivers/tty/Makefile
parent47f58e32a27c647de0963386d2714d570b38e3d3 (diff)
downloadlinux-8a8dabf2dd68caff842d38057097c23bc514ea6e.tar.xz
tty: handle the case where we cannot restore a line discipline
Historically the N_TTY driver could never fail but this has become broken over time. Rather than trying to rewrite half the ldisc layer to fix the breakage introduce a second level of fallback with an N_NULL ldisc which cannot fail, and thus restore the guarantees required by the ldisc layer. We still try and fail to N_TTY first. It's much more useful to find yourself back in your old ldisc (first attempt) or in N_TTY (second attempt), and while I'm not aware of any code out there that makes those assumptions it's good to drive(r) defensively. Signed-off-by: Alan Cox <alan@linux.intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/Makefile')
-rw-r--r--drivers/tty/Makefile3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index f02becdb3e33..8689279afdf1 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \
tty_buffer.o tty_port.o tty_mutex.o \
- tty_ldsem.o tty_baudrate.o tty_jobctrl.o
+ tty_ldsem.o tty_baudrate.o tty_jobctrl.o \
+ n_null.o
obj-$(CONFIG_LEGACY_PTYS) += pty.o
obj-$(CONFIG_UNIX98_PTYS) += pty.o
obj-$(CONFIG_AUDIT) += tty_audit.o