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Commit acd2a847 authored by Jiri Kosina's avatar Jiri Kosina Committed by Greg Kroah-Hartman
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USB: usbserial - fix potential deadlock between write() and IRQ 



USB: usbserial - fix potential deadlock between write() and IRQ

usb_serial_generic_write() doesn't disable interrupts when taking port->lock,
and could therefore deadlock with usb_serial_generic_read_bulk_callback()
being called from interrupt, taking the same lock. Fix it.

Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Acked-by: default avatarLarry Finger <larry.finger@lwfinger.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 8a28dea3

drivers/usb/serial/generic.c

+4 −3
Original line number Diff line number Diff line
@@ -208,14 +208,15 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char * 


	/* only do something if we have a bulk out endpoint */

	if (serial->num_bulk_out) {

		spin_lock_bh(&port->lock);

		unsigned long flags;

		spin_lock_irqsave(&port->lock, flags);

		if (port->write_urb_busy) {

			spin_unlock_bh(&port->lock);

			spin_unlock_irqrestore(&port->lock, flags);

			dbg("%s - already writing", __FUNCTION__);

			return 0;

		}

		port->write_urb_busy = 1;

		spin_unlock_bh(&port->lock);

		spin_unlock_irqrestore(&port->lock, flags);



		count = (count > port->bulk_out_size) ? port->bulk_out_size : count;