Messages in this thread Patch in this message |  | | Date | Mon, 10 Apr 2017 00:52:27 +0800 | From | Wang YanQing <> | Subject | [PATCH] tty:tty_ldisc: add tty_ldisc_lock|unlock to prevent concurrent update to ldisc in tty_ldisc_reinit |
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This patch could fix the issue that tty_reopen in tty_io calling tty_ldisc_reinit without holding tty->ldisc_sem.
Signed-off-by: Wang YanQing <udknight@gmail.com> --- drivers/tty/tty_ldisc.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index b0500a0..b1f7fa5 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -616,6 +616,10 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) if (IS_ERR(ld)) return PTR_ERR(ld); + /* + * Avoid racing set_ldisc or tty_ldisc_release + */ + tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); if (tty->ldisc) { tty_ldisc_close(tty, tty->ldisc); tty_ldisc_put(tty->ldisc); @@ -629,6 +633,7 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) tty_ldisc_put(tty->ldisc); tty->ldisc = NULL; } + tty_ldisc_unlock(tty); return retval; } @@ -672,22 +677,18 @@ void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) /* * Shutdown the current line discipline, and reset it to * N_TTY if need be. - * - * Avoid racing set_ldisc or tty_ldisc_release */ - tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); - if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) tty_reset_termios(tty); - if (tty->ldisc) { - if (reinit) { - if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0) - tty_ldisc_reinit(tty, N_TTY); - } else - tty_ldisc_kill(tty); + if (reinit) { + if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0) + tty_ldisc_reinit(tty, N_TTY); + } else { + tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); + tty_ldisc_kill(tty); + tty_ldisc_unlock(tty); } - tty_ldisc_unlock(tty); } /** -- 1.8.5.6.2.g3d8a54e.dirty
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