Hi Hans,
> Oh what fun (not). The best way to figure out what really is going
> on is to get some usb level traces. Note my first hunch is that what
> you're seeing is a device firmware bug, as this patch together with
> a new libusb (which you seem to also have) will make bulk transfers
> run slightly faster, which might be just enough to overwhelm your
> device ...
Or, the large bulk transfer actually never worked in the first place.
The list you gave me seemed boringly long, so I read the patch more
closely instead. The fix below is the result. Greg, will you please
take it through your tree?
Thanks,
Henrik
>From 40b70394747eea51fdd07cc8213dd6afd24b1b30 Mon Sep 17 00:00:00 2001
From: Henrik Rydberg <rydb...@euromail.se>
Date: Thu, 11 Oct 2012 23:27:04 +0200
Subject: [PATCH] usbdevfs: Fix broken scatter-gather transfer
The recently introduced handling of large bulk transfers is completely
broken; the same user page is read over and over again. Fixed with
this patch.
Cc: sta...@kernel.org
Signed-off-by: Henrik Rydberg <rydb...@euromail.se>
---
drivers/usb/core/devio.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index ebb8a9d..6e58b59 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1172,6 +1172,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct
usbdevfs_urb *uurb,
struct usb_ctrlrequest *dr = NULL;
unsigned int u, totlen, isofrmlen;
int i, ret, is_in, num_sgs = 0, ifnum = -1;
+ void __user *userbuf;
void *buf;
if (uurb->flags & ~(USBDEVFS_URB_ISO_ASAP |
@@ -1333,6 +1334,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct
usbdevfs_urb *uurb,
as->urb->num_sgs = num_sgs;
sg_init_table(as->urb->sg, as->urb->num_sgs);
+ userbuf = uurb->buffer;
totlen = uurb->buffer_length;
for (i = 0; i < as->urb->num_sgs; i++) {
u = (totlen > USB_SG_SIZE) ? USB_SG_SIZE : totlen;
@@ -1344,11 +1346,12 @@ static int proc_do_submiturb(struct dev_state *ps,
struct usbdevfs_urb *uurb,
sg_set_buf(&as->urb->sg[i], buf, u);
if (!is_in) {
- if (copy_from_user(buf, uurb->buffer, u)) {
+ if (copy_from_user(buf, userbuf, u)) {
ret = -EFAULT;
goto error;
}
}
+ userbuf += u;
totlen -= u;
}
} else if (uurb->buffer_length > 0) {
--
1.7.12.2
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