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From:   Alex Dewar <alex.dewar90@gmail.com>
Date:   Tue, 25 Aug 2020 09:14:59 +0100
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Alex Dewar <alex.dewar90@gmail.com>, devel@driverdev.osuosl.org,
        Saiyam Doshi <saiyamdoshi.in@gmail.com>,
        Magnus Damm <damm+renesas@opensource.se>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        YueHaibing <yuehaibing@huawei.com>, linux-kernel@vger.kernel.org,
        "Javier F. Arias" <jarias.linux@gmail.com>,
        "Frank A. Cancio Bello" <frank@generalsoftwareinc.com>,
        Simon Horman <horms+renesas@verge.net.au>
Subject: Re: [PATCH] staging: emxx_udc: Fix passing of NULL to
 dma_alloc_coherent()
Message-ID: <20200825081459.qfvswtep5fkaqai2@lenovo-laptop>
References: <20200824142118.GA223827@mwanda>
 <20200824151920.251446-1-alex.dewar90@gmail.com>
 <20200824155712.4kgxwqiufm2ieboz@medion>
 <20200825073713.GR1793@kadam>
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On Tue, Aug 25, 2020 at 10:37:13AM +0300, Dan Carpenter wrote:
> On Mon, Aug 24, 2020 at 04:57:12PM +0100, Alex Dewar wrote:
> > On Mon, Aug 24, 2020 at 04:19:17PM +0100, Alex Dewar wrote:
> > > In nbu2ss_eq_queue() memory is allocated with dma_alloc_coherent(),
> > > though, strangely, NULL is passed as the struct device* argument. Pass
> > > the UDC's device instead.
> 
> I think passing NULL was always wrong, but it used to not cause an Oops.
> This was changed a year or two ago.
> 
> > > 
> > > Build-tested on x86 only.
> > > 
> > > Fixes: 33aa8d45a4fe ("staging: emxx_udc: Add Emma Mobile USB Gadget driver")
> > > Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> > > ---
> > > 
> > > So I *think* this is the right fix, but I don't have the hardware so
> > > I've only been able to build-test it. My worry is that I could be
> > > passing in the wrong struct device* here, which would squelch the
> > > warning without fixing the breakage.
> > > 
> > > Can someone cleverer than me tell me if this makes sense?
> > > 
> > > - Alex
> > 
> > PS -- I meant to put an RFC in the subject line and an extra tag:
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> 
> I don't know which dev pointer we're supposed to pass...  It would be
> good to find someone to test the patch but if not then applying your
> patch is reasonable.
> 
> But could you search through the file and update the rest as well.
> The dma_free_coherent() needs to be updated and there was a second
> dma_alloc_coherent() in the bug report.
> 
> regards,
> dan carpenter
> 

I can only find the one instance of dma_alloc_coherent(). Was it by any
chance a different warning about the same call....?