Hello Pete,
there's a bug in the usbmon binary reader: When using read() to fetch
the packets and a packet's data is partially read the next read call
will once again return up to len_cap bytes of data. The b_read counter
is not regarded when determining the remaining chunk size.
When dumping USB data with "cat /dev/usbmon0 > usbmon.trace" while
reading from a USB storage device and analyzing the dump file
afterwards it will get out of sync after a couple of packets.
Cheers,
Ingo
Signed-off-by: Ingo van Lil <[email protected]>
---
diff -urN a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
--- a/drivers/usb/mon/mon_bin.c 2008-07-13 23:51:29.000000000 +0200
+++ b/drivers/usb/mon/mon_bin.c 2008-11-13 11:44:03.000000000 +0100
@@ -681,7 +681,7 @@
}
if (rp->b_read >= sizeof(struct mon_bin_hdr)) {
- step_len = min(nbytes, (size_t)ep->len_cap);
+ step_len = min(nbytes, sizeof(struct mon_bin_hdr) + (size_t)ep->len_cap - rp->b_read);
offset = rp->b_out + PKT_SIZE;
offset += rp->b_read - sizeof(struct mon_bin_hdr);
if (offset >= rp->b_size)
On Thu, 13 Nov 2008 13:59:45 +0100, Ingo van Lil <[email protected]> wrote:
> +++ b/drivers/usb/mon/mon_bin.c 2008-11-13 11:44:03.000000000 +0100
> @@ -681,7 +681,7 @@
> }
>
> if (rp->b_read >= sizeof(struct mon_bin_hdr)) {
> - step_len = min(nbytes, (size_t)ep->len_cap);
> + step_len = min(nbytes, sizeof(struct mon_bin_hdr) + (size_t)ep->len_cap - rp->b_read);
> offset = rp->b_out + PKT_SIZE;
I cannot tell right away if this is the best fix, but I'll look
into this. Thanks a lot!
-- Pete
On Thu, 13 Nov 2008 13:59:45 +0100, Ingo van Lil <[email protected]> wrote:
> When dumping USB data with "cat /dev/usbmon0 > usbmon.trace" while
> reading from a USB storage device and analyzing the dump file
> afterwards it will get out of sync after a couple of packets.
I think you nailed the problem. I only want shorter lines.
How about this:
diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
index c9de3f0..e06810a 100644
--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -687,7 +687,10 @@ static ssize_t mon_bin_read(struct file *file, char __user *buf,
}
if (rp->b_read >= sizeof(struct mon_bin_hdr)) {
- step_len = min(nbytes, (size_t)ep->len_cap);
+ step_len = ep->len_cap;
+ step_len -= rp->b_read - sizeof(struct mon_bin_hdr);
+ if (step_len > nbytes)
+ step_len = nbytes;
offset = rp->b_out + PKT_SIZE;
offset += rp->b_read - sizeof(struct mon_bin_hdr);
if (offset >= rp->b_size)
Also, please send me signed-off-by if you want it.
-- Pete
Pete Zaitcev wrote:
>> When dumping USB data with "cat /dev/usbmon0 > usbmon.trace" while
>> reading from a USB storage device and analyzing the dump file
>> afterwards it will get out of sync after a couple of packets.
>
> I think you nailed the problem. I only want shorter lines.
> How about this:
Looks good to me, and works just fine.
Signed-off-by: Ingo van Lil <[email protected]>
Regards,
Ingo