From: "Henrik Rydberg" <rydberg@euromail.se>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Hans de Goede <hdegoede@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Stuge <peter@stuge.se>
Subject: Re: REGRESSION: usbdevfs: Use-scatter-gather-lists-for-large-bulk-transfers
Date: Fri, 12 Oct 2012 17:08:00 +0200 [thread overview]
Message-ID: <20121012150800.GA3097@polaris.bitmath.org> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1210121018390.1605-100000@iolanthe.rowland.org>
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@euromail.se>
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 user
page is read over and over again. Fixed with this patch.
Signed-off-by: Henrik Rydberg <rydberg@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
@@ -1349,6 +1351,7 @@
goto error;
}
}
+ uurb->buffer += u;
totlen -= u;
}
} else if (uurb->buffer_length > 0) {
next prev parent reply other threads:[~2012-10-12 15:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 20:31 REGRESSION: usbdevfs: Use-scatter-gather-lists-for-large-bulk-transfers Henrik Rydberg
2012-10-10 20:34 ` Peter Stuge
2012-10-11 5:44 ` Henrik Rydberg
2012-10-11 6:50 ` Peter Stuge
2012-10-11 6:57 ` Xiaofan Chen
2012-10-11 7:12 ` Peter Stuge
2012-10-11 21:54 ` Henrik Rydberg
2012-10-11 8:21 ` Hans de Goede
2012-10-11 21:37 ` Henrik Rydberg
2012-10-11 21:40 ` Peter Stuge
2012-10-11 21:53 ` Greg Kroah-Hartman
2012-10-12 14:11 ` Hans de Goede
2012-10-12 15:10 ` Henrik Rydberg
2012-10-12 14:25 ` Alan Stern
2012-10-12 15:08 ` Henrik Rydberg [this message]
2012-10-12 15:10 ` Alan Stern
2012-10-14 15:40 ` Hans de Goede
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