linux-kernel - Re: 2.6.33 bugs (USBFS, Intel graphic)

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Message-ID: <20100227052648.GA31418@kroah.com>
Date:	Fri, 26 Feb 2010 21:26:48 -0800
From:	Greg KH <greg@...ah.com>
To:	Markus Rechberger <mrechberger@...il.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-usb@...r.kernel.org, werner@...ane.dyn-o-saur.com,
	Marcus Meissner <meissner@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.33 bugs (USBFS, Intel graphic)

On Fri, Feb 26, 2010 at 09:17:37PM -0800, Greg KH wrote:
> On Sat, Feb 27, 2010 at 05:34:27AM +0100, Markus Rechberger wrote:
> > On Sat, Feb 27, 2010 at 5:29 AM, Linus Torvalds
> > <torvalds@...ux-foundation.org> wrote:
> > >
> > >
> > > On Fri, 26 Feb 2010, Greg KH wrote:
> > >>
> > >> Yes, and that patch didn't touch the iso frames. ?That happens later on
> > >> in the functions that were modified. ?The patch should not have had any
> > >> affect on iso transfers. ?Unless I'm missing something?
> > >
> > > Hmm. What seems to happen is that for an isochronous transfer, the buffer
> > > is split for each microframe. No?
> > >
> > 
> > exactly. and each microframe has its own buffer length identifier.
> > 
> > the current behaviour breaks VMware, QEMU and virtualbox .. probably
> > other things too.
> > 
> > 
> > > So the total length may be in 'urb->actual_length', but the actual data in
> > > the buffer may not be contiguous, because it's created from multiple
> > > smaller frames, some of which might not be full length?
> > >
> > 
> > yes, it's only contiguous for BULK.
> > 
> > > I dunno. That would explain the problem - actual_length is correct, but
> > > the 'copy_to_user()' still doesn't copy all the data, because it's
> > > fragmented.
> > >
> > 
> > no you got it, but your patch does not work. The best way would be to
> > revert it if someone wants to speed up BULK it should go down another
> > path, leaving the old working implementation untouched.
> 
> Hm, so it's back to the original idea of just doing a kzalloc of the
> initial buffer, that should solve the problem that Marcus found.
> 
> I'll go dig that back up and if you could test it, that would be most
> appreciated.

Here, can you try this on top of everything?

thanks,

greg k-h


diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index a678186..252d3b4 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1168,7 +1168,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 		return -ENOMEM;
 	}
 	if (uurb->buffer_length > 0) {
-		as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
+		as->urb->transfer_buffer = kzalloc(uurb->buffer_length,
 				GFP_KERNEL);
 		if (!as->urb->transfer_buffer) {
 			kfree(isopkt);
@@ -1312,9 +1312,9 @@ static int processcompl(struct async *as, void __user * __user *arg)
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer && urb->actual_length)
+	if (as->userbuffer)
 		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->actual_length))
+				 urb->transfer_buffer_length))
 			goto err_out;
 	if (put_user(as->status, &userurb->status))
 		goto err_out;
@@ -1480,9 +1480,9 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer && urb->actual_length)
+	if (as->userbuffer)
 		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->actual_length))
+				 urb->transfer_buffer_length))
 			return -EFAULT;
 	if (put_user(as->status, &userurb->status))
 		return -EFAULT;
--
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