Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: a+ZEyJ/uXKVpIVl2oNfhk7izCcyDcER62fcVafKi9GSdIcx9u6BcR8fxnrDhqT517fUz5hBw/Y
 fm6y/1AFTtYQ==
IronPort-SDR: sR2hXxu8T2lcj7cJ/kH6/2qbXyOJIjGLMP+4uWdN1QkhTbwtAcXE7iVssq6HTcW3wkZRN8rYgE
 tDVXwVNvPB4w==
Subject: Re: [PATCH 17/24] usb: host: xhci: Remove unused variable 'len'
To:     Lee Jones <lee.jones@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org,
        Mathias Nyman <mathias.nyman@intel.com>,
        linux-usb@vger.kernel.org
References: <20210526130037.856068-1-lee.jones@linaro.org>
 <20210526130037.856068-18-lee.jones@linaro.org> <YK9Ju9/kdaRv1jcT@kroah.com>
 <20210527081609.GF543307@dell>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
Autocrypt: addr=mathias.nyman@linux.intel.com; prefer-encrypt=mutual; keydata=
 mQINBFMB0ccBEADd+nZnZrFDsIjQtclVz6OsqFOQ6k0nQdveiDNeBuwyFYykkBpaGekoHZ6f
 lH4ogPZzQ+pzoJEMlRGXc881BIggKMCMH86fYJGfZKWdfpg9O6mqSxyEuvBHKe9eZCBKPvoC
 L2iwygtO8TcXXSCynvXSeZrOwqAlwnxWNRm4J2ikDck5S5R+Qie0ZLJIfaId1hELofWfuhy+
 tOK0plFR0HgVVp8O7zWYT2ewNcgAzQrRbzidA3LNRfkL7jrzyAxDapuejuK8TMrFQT/wW53e
 uegnXcRJaibJD84RUJt+mJrn5BvZ0MYfyDSc1yHVO+aZcpNr+71yZBQVgVEI/AuEQ0+p9wpt
 O9Wt4zO2KT/R5lq2lSz1MYMJrtfFRKkqC6PsDSB4lGSgl91XbibK5poxrIouVO2g9Jabg04T
 MIPpVUlPme3mkYHLZUsboemRQp5/pxV4HTFR0xNBCmsidBICHOYAepCzNmfLhfo1EW2Uf+t4
 L8IowAaoURKdgcR2ydUXjhACVEA/Ldtp3ftF4hTQ46Qhba/p4MUFtDAQ5yeA5vQVuspiwsqB
 BoL/298+V119JzM998d70Z1clqTc8fiGMXyVnFv92QKShDKyXpiisQn2rrJVWeXEIVoldh6+
 J8M3vTwzetnvIKpoQdSFJ2qxOdQ8iYRtz36WYl7hhT3/hwkHuQARAQABtCdNYXRoaWFzIE55
 bWFuIDxtYXRoaWFzLm55bWFuQGdtYWlsLmNvbT6JAjsEEwECACUCGwMGCwkIBwMCBhUIAgkK
 CwQWAgMBAh4BAheABQJTAeo1AhkBAAoJEFiDn/uYk8VJOdIP/jhA+RpIZ7rdUHFIYkHEKzHw
 tkwrJczGA5TyLgQaI8YTCTPSvdNHU9Rj19mkjhUO/9MKvwfoT2RFYqhkrtk0K92STDaBNXTL
 JIi4IHBqjXOyJ/dPADU0xiRVtCHWkBgjEgR7Wihr7McSdVpgupsaXhbZjXXgtR/N7PE0Wltz
 hAL2GAnMuIeJyXhIdIMLb+uyoydPCzKdH6znfu6Ox76XfGWBCqLBbvqPXvk4oH03jcdt+8UG
 2nfSeti/To9ANRZIlSKGjddCGMa3xzjtTx9ryf1Xr0MnY5PeyNLexpgHp93sc1BKxKKtYaT0
 lR6p0QEKeaZ70623oB7Sa2Ts4IytqUVxkQKRkJVWeQiPJ/dZYTK5uo15GaVwufuF8VTwnMkC
 4l5X+NUYNAH1U1bpRtlT40aoLEUhWKAyVdowxW4yGCP3nL5E69tZQQgsag+OnxBa6f88j63u
 wxmOJGNXcwCerkCb+wUPwJzChSifFYmuV5l89LKHgSbv0WHSN9OLkuhJO+I9fsCNvro1Y7dT
 U/yq4aSVzjaqPT3yrnQkzVDxrYT54FLWO1ssFKAOlcfeWzqrT9QNcHIzHMQYf5c03Kyq3yMI
 Xi91hkw2uc/GuA2CZ8dUD3BZhUT1dm0igE9NViE1M7F5lHQONEr7MOCg1hcrkngY62V6vh0f
 RcDeV0ISwlZWuQINBFMB0ccBEACXKmWvojkaG+kh/yipMmqZTrCozsLeGitxJzo5hq9ev31N
 2XpPGx4AGhpccbco63SygpVN2bOd0W62fJJoxGohtf/g0uVtRSuK43OTstoBPqyY/35+VnAV
 oA5cnfvtdx5kQPIL6LRcxmYKgN4/3+A7ejIxbOrjWFmbWCC+SgX6mzHHBrV0OMki8R+NnrNa
 NkUmMmosi7jBSKdoi9VqDqgQTJF/GftvmaZHqgmVJDWNrCv7UiorhesfIWPt1O/AIk9luxlE
 dHwkx5zkWa9CGYvV6LfP9BznendEoO3qYZ9IcUlW727Le80Q1oh69QnHoI8pODDBBTJvEq1h
 bOWcPm/DsNmDD8Rwr/msRmRyIoxjasFi5WkM/K/pzujICKeUcNGNsDsEDJC5TCmRO/TlvCvm
 0X+vdfEJRZV6Z+QFBflK1asUz9QHFre5csG8MyVZkwTR9yUiKi3KiqQdaEu+LuDD2CGF5t68
 xEl66Y6mwfyiISkkm3ETA4E8rVZP1rZQBBm83c5kJEDvs0A4zrhKIPTcI1smK+TWbyVyrZ/a
 mGYDrZzpF2N8DfuNSqOQkLHIOL3vuOyx3HPzS05lY3p+IIVmnPOEdZhMsNDIGmVorFyRWa4K
 uYjBP/W3E5p9e6TvDSDzqhLoY1RHfAIadM3I8kEx5wqco67VIgbIHHB9DbRcxQARAQABiQIf
 BBgBAgAJBQJTAdHHAhsMAAoJEFiDn/uYk8VJb7AQAK56tgX8V1Wa6RmZDmZ8dmBC7W8nsMRz
 PcKWiDSMIvTJT5bygMy1lf7gbHXm7fqezRtSfXAXr/OJqSA8LB2LWfThLyuuCvrdNsQNrI+3
 D+hjHJjhW/4185y3EdmwwHcelixPg0X9EF+lHCltV/w29Pv3PiGDkoKxJrnOpnU6jrwiBebz
 eAYBfpSEvrCm4CR4hf+T6MdCs64UzZnNt0nxL8mLCCAGmq1iks9M4bZk+LG36QjCKGh8PDXz
 9OsnJmCggptClgjTa7pO6040OW76pcVrP2rZrkjo/Ld/gvSc7yMO/m9sIYxLIsR2NDxMNpmE
 q/H7WO+2bRG0vMmsndxpEYS4WnuhKutoTA/goBEhtHu1fg5KC+WYXp9wZyTfeNPrL0L8F3N1
 BCEYefp2JSZ/a355X6r2ROGSRgIIeYjAiSMgGAZMPEVsdvKsYw6BH17hDRzltNyIj5S0dIhb
 Gjynb3sXforM/GVbr4mnuxTdLXQYlj2EJ4O4f0tkLlADT7podzKSlSuZsLi2D+ohKxtP3U/r
 42i8PBnX2oAV0UIkYk7Oel/3hr0+BP666SnTls9RJuoXc7R5XQVsomqXID6GmjwFQR5Wh/RE
 IJtkiDAsk37cfZ9d1kZ2gCQryTV9lmflSOB6AFZkOLuEVSC5qW8M/s6IGDfYXN12YJaZPptJ fiD/
Message-ID: <5958f870-1834-3132-a729-2b26a84349ea@linux.intel.com>
Date:   Thu, 27 May 2021 12:23:24 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20210527081609.GF543307@dell>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 27.5.2021 11.16, Lee Jones wrote:
> On Thu, 27 May 2021, Greg Kroah-Hartman wrote:
> 
>> On Wed, May 26, 2021 at 02:00:30PM +0100, Lee Jones wrote:
>>> Fixes the following W=1 kernel build warning(s):
>>>
>>>  drivers/usb/host/xhci.c: In function ‘xhci_unmap_temp_buf’:
>>>  drivers/usb/host/xhci.c:1349:15: warning: variable ‘len’ set but not used [-Wunused-but-set-variable]
>>>
>>> Cc: Mathias Nyman <mathias.nyman@intel.com>
>>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>> Cc: linux-usb@vger.kernel.org
>>> Signed-off-by: Lee Jones <lee.jones@linaro.org>
>>> ---
>>>  drivers/usb/host/xhci.c | 9 ++++-----
>>>  1 file changed, 4 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>>> index 27283654ca080..ac2a7d4288883 100644
>>> --- a/drivers/usb/host/xhci.c
>>> +++ b/drivers/usb/host/xhci.c
>>> @@ -1346,7 +1346,6 @@ static bool xhci_urb_temp_buffer_required(struct usb_hcd *hcd,
>>>  
>>>  static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb)
>>>  {
>>> -	unsigned int len;
>>>  	unsigned int buf_len;
>>>  	enum dma_data_direction dir;
>>>  
>>> @@ -1362,10 +1361,10 @@ static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb)
>>>  				 dir);
>>>  
>>>  	if (usb_urb_dir_in(urb))
>>> -		len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs,
>>> -					   urb->transfer_buffer,
>>> -					   buf_len,
>>> -					   0);
>>> +		sg_pcopy_from_buffer(urb->sg, urb->num_sgs,
>>> +				     urb->transfer_buffer,
>>> +				     buf_len,
>>> +				     0);
>>
>> Sorry, but no, I keep rejecting this over and over, it needs to handle
>> the error handling properly and not paper over it like this :(
> 
> Will fix.
> 
>> All the bots keep tripping up on it, you are not alone.
> 

This is getting a lot of attention. Something like this should fix it:

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 27283654ca08..306ab81421fd 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1361,12 +1361,16 @@ static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb)
 				 urb->transfer_buffer_length,
 				 dir);
 
-	if (usb_urb_dir_in(urb))
+	if (usb_urb_dir_in(urb)) {
 		len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs,
 					   urb->transfer_buffer,
 					   buf_len,
 					   0);
-
+		if (len != buf_len) {
+			xhci_dbg(xhci, "Copy from tmp buf to urb sg list failed\n");
+			urb->actual_length = len;
+		}
+	}
 	urb->transfer_flags &= ~URB_DMA_MAP_SINGLE;
 	kfree(urb->transfer_buffer);
 	urb->transfer_buffer = NULL;
 
urb->actual_length is now properly set.
The debug level message will help me find the cause if we ever need
to debug oddly behaving devices.

Note this is a very rarly taken codepath for quirky xHC harware that
can't handle a specific sequence of buffer lengths queued.

I can write a proper commit message and push this forward

-Mathias