Re: REGRESSION: usbdevfs: Use-scatter-gather-lists-for-large-bulk-transfers
From: Hans de Goede
Date: Sun Oct 14 2012 - 11:44:57 EST
Hi,
On 10/12/2012 05:08 PM, Henrik Rydberg wrote:
Hi Alan,
Instead of introducing a new local variable, why not simply update
uurb->buffer? That's what we do elsewhere in the code.
It seemed fragile, due to these scary lines:
if (is_in && uurb->buffer_length > 0)
as->userbuffer = uurb->buffer;
else
as->userbuffer = NULL;
I suppose it works in this particular case. How is the
USBDEVFS_URB_TYPE_CONTROL case supposed to work here?
I can certainly change the patch if preferred. Tested and attached
below.
Thanks,
Henrik
From 40b70394747eea51fdd07cc8213dd6afd24b1b30 Mon Sep 17 00:00:00 2001
From: Henrik Rydberg <rydberg@xxxxxxxxxxx>
Date: Thu, 11 Oct 2012 23:27:04 +0200
Subject: [PATCH v2] usbdevfs: Fix broken scatter-gather transfer
The handling of large output bulk transfers is broken; the same u
page is read over and over again. Fixed with this patch.
Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
---
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
@@ -1349,6 +1351,7 @@
goto error;
}
}
+ uurb->buffer += u;
I know you've already fixed this in the next revision, but still:
NAK, this will break large, split input transfers as it well
set as->userbuffer to the end of the buffer instead of the beginning!
Regards,
Hans
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