This is a note to let you know that I've just added the patch titled
USB: serial: keyspan_pda: fix write deadlock
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 7353cad7ee4deaefc16e94727e69285563e219f6 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@xxxxxxxxxx>
Date: Sun, 25 Oct 2020 18:45:48 +0100
Subject: USB: serial: keyspan_pda: fix write deadlock
The write() callback can be called in interrupt context (e.g. when used
as a console) so interrupts must be disabled while holding the port lock
to prevent a possible deadlock.
Fixes: e81ee637e4ae ("usb-serial: possible irq lock inversion (PPP vs. usb/serial)")
Fixes: 507ca9bc0476 ("[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.")
Cc: stable <stable@xxxxxxxxxxxxxxx> # 2.6.19
Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/usb/serial/keyspan_pda.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 2d5ad579475a..17b60e5a9f1f 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -443,6 +443,7 @@ static int keyspan_pda_write(struct tty_struct *tty,
int request_unthrottle = 0;
int rc = 0;
struct keyspan_pda_private *priv;
+ unsigned long flags;
priv = usb_get_serial_port_data(port);
/* guess how much room is left in the device's ring buffer, and if we
@@ -462,13 +463,13 @@ static int keyspan_pda_write(struct tty_struct *tty,
the TX urb is in-flight (wait until it completes)
the device is full (wait until it says there is room)
*/
- spin_lock_bh(&port->lock);
+ spin_lock_irqsave(&port->lock, flags);
if (!test_bit(0, &port->write_urbs_free) || priv->tx_throttled) {
- spin_unlock_bh(&port->lock);
+ spin_unlock_irqrestore(&port->lock, flags);
return 0;
}
clear_bit(0, &port->write_urbs_free);
- spin_unlock_bh(&port->lock);
+ spin_unlock_irqrestore(&port->lock, flags);
/* At this point the URB is in our control, nobody else can submit it
again (the only sudden transition was the one from EINPROGRESS to
--
2.29.2
