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SubjectRe: [PATCH v2] mm: fix null dev in dma_pool_create()
On 11/13/12 7:58 PM, Andrew Morton wrote:
> I'm not sure that I really suggested doing this :(

You suggested WARN_ON_ONCE(!dev); I changed it to WARN_ON(!dev) and
kept the NULL check..

> We know there are a few scruffy drivers which are passing in dev==0.
>
> Those drivers don't oops because nobody is testing them on NUMA
> systems.
>
> With this patch, the kernel will now cause runtime warnings to be
> emitted from those drivers. Even on non-NUMA systems.
>
> This is a problem! What will happen is that this code will get
> released by Linus and will propagate to users mainly via distros and
> eventually end-user bug reports will trickle back saying "hey, I got
> this warning". Slowly people will fix the scruffy drivers and those
> fixes will propagate out from Linus's tree into -stable and then into
> distros and then into the end-users hands.
>
> This is *terribly* inefficient! It's a lot of work for a lot of people
> and it involves long delays.
>
> So let's not do any of that! Let us try to get those scruffy drivers
> fixed up *before* we add this warning.
>
> As a nice side-effect of that work, we can then clean up the dmapool
> code so it doesn't need to worry about handling the dev==0 special
> case.
>
> So. To start this off, can you please generate a list of the offending
> drivers? Then we can hunt down the maintainers and we'll see what can be
> done.

I like this plan.

Here's the list of drivers that invoke dma_pool_create() with NULL dev,
as well as possible fixes, from previous emails.

* arch/arm/mach-s3c64xx/dma.c

Use dmac->dev for dma_pool_create() in s3c64xx_dma_init1()? Probably
need to add ->dma_pool to struct s3c64xx_dmac.

* drivers/usb/gadget/amd5536udc.c (2)

Use dev->gadget.dev or dev->pdev->dev for dma_pool_create()? Also move
the init_dma_pools() call after the assignments in udc_pci_probe().

* drivers/net/wan/ixp4xx_hss.c
* drivers/net/ethernet/xscale/ixp4xx_eth.c

Use port->netdev->dev for dma_pool_create()?


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