USB: option: fix usage of urb->status abuse

Might fix bug 8561

On Mon, 4 Jun 2007, Paulo Pereira wrote:

> The patch that you send is not resolving the problem... :(
> I stil have Kernel panic after 45/60 min of work with Ktorrent/Amule...
>
> The Drump is:
>
> Call Trace:
> [<c055fb36>] usb_hcd_submit+0xb1/0x763
> [<f9276488>] ipt_do_table+0x2c7/0x2ef [ip_tables]
> [<f929a6d7>] nf_ct_deliver_cached_events+0x41/0x96 [nf_conntrak]
> [<f9288254>] ipv4_confirm+0x36/0c3b [nf_conntrack_ipv4]
> [<c05ce7c2>] tcp_v4_rcv+0x827/0x899
> [<c05afcc0>] nf_hook_slow+0x4d/0xb5
> [<c042826f>] irq_enter+0x19/0x23
> [<c042826f>] irq_enter+0x19/0x23
> [<c040794c>] do_IRQ+0xbd/0xd1
> [<f90893c9>] option_write+0xa7/0xef [option]

Okay, from this it looks like there's a problem in the option.c serial
driver.  Glancing at the code, it's obvious why: The thing totally
abuses the USB API.

Try applying this patch; it should help.

From: Alan Stern <stern@rowland.harvard.edu>
Cc: Paulo Pereira <pfmp.404@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/option.c

@@ -38,6 +38,7 @@
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/module.h>
+#include <linux/bitops.h>
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 
@@ -240,6 +241,7 @@ struct option_port_private {
 	/* Output endpoints and buffer for this port */
 	struct urb *out_urbs[N_OUT_URB];
 	char out_buffer[N_OUT_URB][OUT_BUFLEN];
+	unsigned long out_busy;		/* Bit vector of URBs in use */
 
 	/* Settings for the port */
 	int rts_state;	/* Handshaking pins (outputs) */
@@ -370,7 +372,7 @@ static int option_write(struct usb_serial_port *port,
 			todo = OUT_BUFLEN;
 
 		this_urb = portdata->out_urbs[i];
-		if (this_urb->status == -EINPROGRESS) {
+		if (test_and_set_bit(i, &portdata->out_busy)) {
 			if (time_before(jiffies,
 					portdata->tx_start_time[i] + 10 * HZ))
 				continue;
@@ -394,6 +396,7 @@ static int option_write(struct usb_serial_port *port,
 			dbg("usb_submit_urb %p (write bulk) failed "
 				"(%d, has %d)", this_urb,
 				err, this_urb->status);
+			clear_bit(i, &portdata->out_busy);
 			continue;
 		}
 		portdata->tx_start_time[i] = jiffies;
@@ -446,12 +449,23 @@ static void option_indat_callback(struct urb *urb)
 static void option_outdat_callback(struct urb *urb)
 {
 	struct usb_serial_port *port;
+	struct option_port_private *portdata;
+	int i;
 
 	dbg("%s", __FUNCTION__);
 
 	port = (struct usb_serial_port *) urb->context;
 
 	usb_serial_port_softint(port);
+
+	portdata = usb_get_serial_port_data(port);
+	for (i = 0; i < N_OUT_URB; ++i) {
+		if (portdata->out_urbs[i] == urb) {
+			smp_mb__before_clear_bit();
+			clear_bit(i, &portdata->out_busy);
+			break;
+		}
+	}
 }
 
 static void option_instat_callback(struct urb *urb)
@@ -518,7 +532,7 @@ static int option_write_room(struct usb_serial_port *port)
 
 	for (i=0; i < N_OUT_URB; i++) {
 		this_urb = portdata->out_urbs[i];
-		if (this_urb && this_urb->status != -EINPROGRESS)
+		if (this_urb && !test_bit(i, &portdata->out_busy))
 			data_len += OUT_BUFLEN;
 	}
 
@@ -537,7 +551,7 @@ static int option_chars_in_buffer(struct usb_serial_port *port)
 
 	for (i=0; i < N_OUT_URB; i++) {
 		this_urb = portdata->out_urbs[i];
-		if (this_urb && this_urb->status == -EINPROGRESS)
+		if (this_urb && test_bit(i, &portdata->out_busy))
 			data_len += this_urb->transfer_buffer_length;
 	}
 	dbg("%s: %d", __FUNCTION__, data_len);