The tty_port struct is part of the rpmsg_tty_port structure.
The issue is that the rpmsg_tty_port structure is freed on
rpmsg_tty_remove while it is still referenced in the tty_struct.
Its release is not predictable due to workqueues.
For instance following ftrace shows that rpmsg_tty_close is called after
rpmsg_tty_release_cport:
nr_test.sh-389 [000] ..... 212.093752: rpmsg_tty_remove <-rpmsg_dev_
remove
cat-1191 [001] ..... 212.095697: tty_release <-__fput
nr_test.sh-389 [000] ..... 212.099166: rpmsg_tty_release_cport <-rpm
sg_tty_remove
cat-1191 [001] ..... 212.115352: rpmsg_tty_close <-tty_release
cat-1191 [001] ..... 212.115371: release_tty <-tty_release_str
As consequence, the port must be free only when user has released the TTY
interface.
This path :
- Introduce the .destruct port tty ops function to release the allocated
rpmsg_tty_port structure.
- Introduce the .hangup tty ops function to call tty_port_hangup.
- Manages the tty port refcounting to trig the .destruct port ops,
- Introduces the rpmsg_tty_cleanup function to ensure that the TTY is
removed before decreasing the port refcount.
Fixes: 7c0408d805 ("tty: add rpmsg driver")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20220104163545.34710-1-arnaud.pouliquen@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I5616481fa97807c954f03cd1dfdff206605b65d3
(cherry picked from commit db7f19c0aa)
[Jiahang: Resolving type conflict in drivers/tty/rpmsg_tty.c ]
Signed-off-by: Jiahang Zheng <jiahang.zheng@rock-chips.com>
Arnaud Pouliquen
ffdcf653d8