Re: [PATCH] isp1362-hcd.c: usb message always saved in case of underrun
From: Claudio Scordino
Date: Fri Jul 20 2012 - 06:26:18 EST
Il 20/07/2012 00:58, Greg KH ha scritto:
On Wed, Jul 18, 2012 at 10:53:09AM +0200, Claudio Scordino wrote:
Il 06/07/2012 19:41, Greg KH ha scritto:
On Wed, Jun 27, 2012 at 06:01:39PM +0200, Claudio Scordino wrote:
Hi Olav,
please find below a patch for the isp1362-hcd.c driver to always
save the message in case of underrun. More information is provided
inside the patch comment. Let us know if you need any further
information.
Best regards,
Claudio
Subject: isp1362-hcd.c: usb message always saved in case of underrun
From: Bruno Morelli<bruno@xxxxxxxxxxxxxxx>
The usb message must be saved also in case the USB endpoint is not a
control endpoint (i.e., "endpoint 0"), otherwise in some circumstances
we don't have a payload in case of error.
The patch has been created by tracing with usbmon the different error
messages generated by this driver with respect to the ehci-hcd driver.
Signed-off-by: Bruno Morelli<bruno@xxxxxxxxxxxxxxx>
Signed-off-by: Claudio Scordino<claudio@xxxxxxxxxxxxxxx>
Tested-by: Bruno Morelli<bruno@xxxxxxxxxxxxxxx>
---
drivers/usb/host/isp1362-hcd.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/host/isp1362-hcd.c b/drivers/usb/host/isp1362-hcd.c
index 2ed112d..61bf1b2 100644
--- a/drivers/usb/host/isp1362-hcd.c
+++ b/drivers/usb/host/isp1362-hcd.c
@@ -543,13 +543,14 @@ static void postproc_ep(struct isp1362_hcd *isp1362_hcd, struct isp1362_ep *ep)
usb_pipein(urb->pipe) ? "IN" : "OUT", ep->nextpid,
short_ok ? "" : "not_",
PTD_GET_COUNT(ptd), ep->maxpacket, len);
+ /* save the data underrun error code for later and
+ * proceed with the status stage
+ */
+ urb->actual_length += PTD_GET_COUNT(ptd);
+ BUG_ON(urb->actual_length>
+ urb->transfer_buffer_length);
Please NEVER crash the machine in a driver like this, it's bad and can
cause problems. Yes, I know you are just moving it from the lines
below:
if (usb_pipecontrol(urb->pipe)) {
ep->nextpid = USB_PID_ACK;
- /* save the data underrun error code for later and
- * proceed with the status stage
- */
- urb->actual_length += PTD_GET_COUNT(ptd);
- BUG_ON(urb->actual_length> urb->transfer_buffer_length);
But really, it should not be in the driver at all. Please remove it, at
the most, do a WARN_ON() so that someone can see the problem and at
least report it.
Actually, what is this checking? How can someone recover from it? Who
is this check for? The developer of this driver? Another driver?
Hardware developer? End user? Who would be able to fix the problem if
this happens?
As it is, I can't take it, sorry.
Hi Greg.
I understand. As you have already said, this driver is full of BUG_ON
statements.
So, we can shift just the assignment as in the patch below, to have a
correct behavior, leaving the BUG_ON where it already is. Then, we may
propose a different patch to change BUG_ONs to WARN_ONs.
Your updated patch is much better, thanks.
But it doesn't apply to my tree right now. Can you please refresh it
against the usb-next tree and resend it?
Actually, I did.
So, this means that I'm using the wrong tree...
I'm using the "usb-next" branch available on your tree at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
Is this the wrong one ?
Many thanks,
Claudio
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