From: Tyrel Datwyler <tyreld@linux.ibm.com>
To: gregkh@linuxfoundation.org
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>,
Jason Yan <yanaijie@huawei.com>,
"open list:HYPERVISOR VIRTUAL CONSOLE DRIVER"
<linuxppc-dev@lists.ozlabs.org>,
open list <linux-kernel@vger.kernel.org>,
Joe Perches <joe@perches.com>, Jiri Slaby <jirislaby@kernel.org>
Subject: [PATCH] tty: hvcs: Don't NULL tty->driver_data until hvcs_cleanup()
Date: Thu, 20 Aug 2020 18:46:38 -0500 [thread overview]
Message-ID: <20200820234643.70412-1-tyreld@linux.ibm.com> (raw)
The code currently NULLs tty->driver_data in hvcs_close() with the
intent of informing the next call to hvcs_open() that device needs to be
reconfigured. However, when hvcs_cleanup() is called we copy hvcsd from
tty->driver_data which was previoulsy NULLed by hvcs_close() and our
call to tty_port_put(&hvcsd->port) doesn't actually do anything since
&hvcsd->port ends up translating to NULL by chance. This has the side
effect that when hvcs_remove() is called we have one too many port
references preventing hvcs_destuct_port() from ever being called. This
also prevents us from reusing the /dev/hvcsX node in a future
hvcs_probe() and we can eventually run out of /dev/hvcsX devices.
Fix this by waiting to NULL tty->driver_data in hvcs_cleanup().
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
drivers/tty/hvc/hvcs.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
index 55105ac38f89..509d1042825a 100644
--- a/drivers/tty/hvc/hvcs.c
+++ b/drivers/tty/hvc/hvcs.c
@@ -1216,13 +1216,6 @@ static void hvcs_close(struct tty_struct *tty, struct file *filp)
tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
- /*
- * This line is important because it tells hvcs_open that this
- * device needs to be re-configured the next time hvcs_open is
- * called.
- */
- tty->driver_data = NULL;
-
free_irq(irq, hvcsd);
return;
} else if (hvcsd->port.count < 0) {
@@ -1237,6 +1230,13 @@ static void hvcs_cleanup(struct tty_struct * tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
+ /*
+ * This line is important because it tells hvcs_open that this
+ * device needs to be re-configured the next time hvcs_open is
+ * called.
+ */
+ tty->driver_data = NULL;
+
tty_port_put(&hvcsd->port);
}
--
2.27.0
next reply other threads:[~2020-08-20 23:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 23:46 Tyrel Datwyler [this message]
2020-08-21 21:08 ` [PATCH] tty: hvcs: Don't NULL tty->driver_data until hvcs_cleanup() Tyrel Datwyler
2020-09-14 5:35 ` Jiri Slaby
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