Re: [PATCH] tty: hvcs: Don't NULL tty->driver_data until hvcs_cleanup()
From: Tyrel Datwyler <tyreld@linux.ibm.com>
Date: 2020-08-21 21:09:05
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On 8/20/20 4:46 PM, Tyrel Datwyler wrote:
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().
I just realized I neglected a Fixes tag.
Fixes: 27bf7c43a19c ("TTY: hvcs, add tty install")
-Tyrel
quoted hunk ↗ jump to hunk
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); }