Messages in this thread | | | Subject | Re: use exact allocation for dma coherent memory | From | Arend Van Spriel <> | Date | Tue, 2 Jul 2019 11:48:44 +0200 |
| |
On 7/1/2019 10:48 AM, Christoph Hellwig wrote: > On Fri, Jun 14, 2019 at 03:47:10PM +0200, Christoph Hellwig wrote: >> Switching to a slightly cleaned up alloc_pages_exact is pretty easy, >> but it turns out that because we didn't filter valid gfp_t flags >> on the DMA allocator, a bunch of drivers were passing __GFP_COMP >> to it, which is rather bogus in too many ways to explain. Arm has >> been filtering it for a while, but this series instead tries to fix >> the drivers and warn when __GFP_COMP is passed, which makes it much >> larger than just adding the functionality. > > Dear driver maintainers, > > can you look over the patches touching your drivers, please? I'd > like to get as much as possible of the driver patches into this > merge window, so that it can you through your maintainer trees.
You made me look ;-) Actually not touching my drivers so I'm off the hook. However, I was wondering if drivers could know so I decided to look into the DMA-API.txt documentation which currently states:
""" The flag parameter (dma_alloc_coherent() only) allows the caller to specify the ``GFP_`` flags (see kmalloc()) for the allocation (the implementation may choose to ignore flags that affect the location of the returned memory, like GFP_DMA). """
I do expect you are going to change that description as well now that you are going to issue a warning on __GFP_COMP. Maybe include that in patch 15/16 where you introduce that warning.
Regards, Arend
| |