From 8e8dce065088833fc418bfa5fbf035cb0726c04c Mon Sep 17 00:00:00 2001 From: David VomLehn Date: Fri, 28 Aug 2009 12:54:27 -0700 Subject: USB: use kfifo to buffer usb-generic serial writes When do_output_char() attempts to write a carriage return/line feed sequence, it first checks to see how much buffer room is available. If there are at least two characters free, it will write the carriage return/line feed with two calls to tty_put_char(). It calls the tty_operation functions write() for devices that don't support the tty_operations function put_char(). If the USB generic serial device's write URB is not in use, it will return the buffer size when asked how much room is available. The write() of the carriage return will cause it to mark the write URB busy, so the subsequent write() of the line feed will be ignored. This patch uses the kfifo infrastructure to implement a write FIFO that accurately returns the amount of space available in the buffer. Signed-off-by: David VomLehn Signed-off-by: Greg Kroah-Hartman --- include/linux/usb/serial.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/usb') diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h index 7b85e327af9..c17eb64d721 100644 --- a/include/linux/usb/serial.h +++ b/include/linux/usb/serial.h @@ -59,6 +59,7 @@ enum port_dev_state { * @bulk_out_buffer: pointer to the bulk out buffer for this port. * @bulk_out_size: the size of the bulk_out_buffer, in bytes. * @write_urb: pointer to the bulk out struct urb for this port. + * @write_fifo: kfifo used to buffer outgoing data * @write_urb_busy: port`s writing status * @bulk_out_endpointAddress: endpoint address for the bulk out pipe for this * port. @@ -96,6 +97,7 @@ struct usb_serial_port { unsigned char *bulk_out_buffer; int bulk_out_size; struct urb *write_urb; + struct kfifo *write_fifo; int write_urb_busy; __u8 bulk_out_endpointAddress; -- cgit v1.2.3-70-g09d2