From: Wang YanQing <udknight@gmail.com>
To: gregkh@linuxfoundation.org
Cc: jslaby@suse.com, linux-kernel@vger.kernel.org, mikey@neuling.org,
viro@ZenIV.linux.org.uk, johan@kernel.org,
peter@hurleysoftware.com, alex.popov@linux.com, robh@kernel.org,
mpatocka@redhat.com, dvyukov@google.com,
benh@kernel.crashing.org
Subject: [PATCH] tty:tty_ldisc: add tty_ldisc_lock|unlock to prevent concurrent update to ldisc in tty_ldisc_reinit
Date: Mon, 10 Apr 2017 00:52:27 +0800 [thread overview]
Message-ID: <20170409165227.GA7945@udknight> (raw)
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
reply other threads:[~2017-04-09 16:54 UTC|newest]
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