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From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Christoph Hellwig <hch@infradead.org>
Cc: yvahkhfo.1df7f8c2@hashmail.org, security@kernel.org,
	linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: usb zero copy dma handling
Date: Thu, 8 Aug 2019 17:57:34 +0100	[thread overview]
Message-ID: <20190808165734.GG5193@shell.armlinux.org.uk> (raw)
In-Reply-To: <20190808161015.GA8470@infradead.org>

On Thu, Aug 08, 2019 at 09:10:15AM -0700, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:46:36AM +0200, yvahkhfo.1df7f8c2@hashmail.org wrote:
> > --- a/drivers/usb/core/devio.c
> > +++ b/drivers/usb/core/devio.c
> > @@ -238,9 +238,14 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
> >  	usbm->vma_use_count = 1;
> >  	INIT_LIST_HEAD(&usbm->memlist);
> >  
> > +#ifdef CONFIG_X86
> >  	if (remap_pfn_range(vma, vma->vm_start,
> >  			virt_to_phys(usbm->mem) >> PAGE_SHIFT,
> >  			size, vma->vm_page_prot) < 0) {
> > +#else /* !CONFIG_X86 */
> > +	if (dma_mmap_coherent(ps->dev->bus->sysdev, 
> > +			vma, mem, dma_handle, size) < 0) {
> > +#endif /* !CONFIG_X86 */
> 
> Doing the dma_mmap_coherent unconditionally is the right thing here.

So what if usbm->mem is from kmalloc because the host doesn't support DMA?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Christoph Hellwig <hch@infradead.org>
Cc: yvahkhfo.1df7f8c2@hashmail.org, linux-usb@vger.kernel.org,
	security@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: usb zero copy dma handling
Date: Thu, 8 Aug 2019 17:57:34 +0100	[thread overview]
Message-ID: <20190808165734.GG5193@shell.armlinux.org.uk> (raw)
In-Reply-To: <20190808161015.GA8470@infradead.org>

On Thu, Aug 08, 2019 at 09:10:15AM -0700, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:46:36AM +0200, yvahkhfo.1df7f8c2@hashmail.org wrote:
> > --- a/drivers/usb/core/devio.c
> > +++ b/drivers/usb/core/devio.c
> > @@ -238,9 +238,14 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
> >  	usbm->vma_use_count = 1;
> >  	INIT_LIST_HEAD(&usbm->memlist);
> >  
> > +#ifdef CONFIG_X86
> >  	if (remap_pfn_range(vma, vma->vm_start,
> >  			virt_to_phys(usbm->mem) >> PAGE_SHIFT,
> >  			size, vma->vm_page_prot) < 0) {
> > +#else /* !CONFIG_X86 */
> > +	if (dma_mmap_coherent(ps->dev->bus->sysdev, 
> > +			vma, mem, dma_handle, size) < 0) {
> > +#endif /* !CONFIG_X86 */
> 
> Doing the dma_mmap_coherent unconditionally is the right thing here.

So what if usbm->mem is from kmalloc because the host doesn't support DMA?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-08-08 16:57 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08  8:46 usb zero copy dma handling yvahkhfo.1df7f8c2
2019-08-08  8:46 ` yvahkhfo.1df7f8c2
2019-08-08  8:58 ` Greg KH
2019-08-08  8:58   ` Greg KH
2019-08-08  9:46   ` Robin Murphy
2019-08-08  9:46     ` Robin Murphy
2019-08-08 10:07     ` Greg KH
2019-08-08 10:07       ` Greg KH
2019-08-08 10:43       ` Robin Murphy
2019-08-08 10:43         ` Robin Murphy
2019-08-08 13:05       ` Greg KH
2019-08-08 13:05         ` Greg KH
2019-08-08  9:59   ` Russell King - ARM Linux admin
2019-08-08  9:59     ` Russell King - ARM Linux admin
2019-08-08 10:02     ` Oliver Neukum
2019-08-08 10:02       ` Oliver Neukum
2019-08-08 16:10 ` Christoph Hellwig
2019-08-08 16:10   ` Christoph Hellwig
2019-08-08 16:12   ` Christoph Hellwig
2019-08-08 16:12     ` Christoph Hellwig
2019-08-08 16:57   ` Russell King - ARM Linux admin [this message]
2019-08-08 16:57     ` Russell King - ARM Linux admin
  -- strict thread matches above, loose matches on Subject: below --
2019-07-27 13:57 yvahknez.7f7d2ff0

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