| Message ID | 20191002212257.196849-1-salyzyn@android.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: export cma alloc and release | expand |
On Wed, Oct 02, 2019 at 02:22:48PM -0700, Mark Salyzyn wrote: > Some drivers can not be turned into a module without cma_alloc and > cma_release exported. Examples include ion, and we also found some > out of tree infiniband and camera drivers. > > Signed-off-by: Mark Salyzyn <salyzyn@android.com> > Cc: kernel-team@android.com > Cc: linux-kernel@vger.kernel.org > --- > mm/cma.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/cma.c b/mm/cma.c > index 7fe0b8356775..65d830eea3b1 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -500,6 +500,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > pr_debug("%s(): returned %p\n", __func__, page); > return page; > } > +EXPORT_SYMBOL_GPL(cma_alloc); > > /** > * cma_release() - release allocated pages > @@ -533,6 +534,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count) > > return true; > } > +EXPORT_SYMBOL_GPL(cma_release); Aren't drivers supposed to use the DMA API for such allocations rather than invoking cma_*() directly?
On Thu, Oct 03, 2019 at 09:55:28AM +0100, Catalin Marinas wrote: > Aren't drivers supposed to use the DMA API for such allocations rather > than invoking cma_*() directly? Yes, they are.
On 10/5/19 1:37 AM, Christoph Hellwig wrote: > On Thu, Oct 03, 2019 at 09:55:28AM +0100, Catalin Marinas wrote: >> Aren't drivers supposed to use the DMA API for such allocations rather >> than invoking cma_*() directly? > Yes, they are. We have an engineer assigned to rewriting the ion memory driver to use dma_buf interfaces. Hopefully that effort will solve the problem of requiring these interfaces to be exported so that that driver (and others) can be modularized. Thanks for the reviews, drop this patch from the list and we will regroup, and accept that standing code in the kernel can not be modularized for the moment. Sincerely -- Mark Salyzyn
On Mon, Oct 07, 2019 at 09:50:31AM -0700, Mark Salyzyn wrote: > On 10/5/19 1:37 AM, Christoph Hellwig wrote: >> On Thu, Oct 03, 2019 at 09:55:28AM +0100, Catalin Marinas wrote: >>> Aren't drivers supposed to use the DMA API for such allocations rather >>> than invoking cma_*() directly? >> Yes, they are. > > We have an engineer assigned to rewriting the ion memory driver to use > dma_buf interfaces. Hopefully that effort will solve the problem of > requiring these interfaces to be exported so that that driver (and others) > can be modularized. > > Thanks for the reviews, drop this patch from the list and we will regroup, > and accept that standing code in the kernel can not be modularized for the > moment. How is that different from the "DMA-BUF Heaps (destaging ION)" series floating around?
On 10/7/19 9:53 AM, Christoph Hellwig wrote: > On Mon, Oct 07, 2019 at 09:50:31AM -0700, Mark Salyzyn wrote: >> On 10/5/19 1:37 AM, Christoph Hellwig wrote: >>> On Thu, Oct 03, 2019 at 09:55:28AM +0100, Catalin Marinas wrote: >>>> Aren't drivers supposed to use the DMA API for such allocations rather >>>> than invoking cma_*() directly? >>> Yes, they are. >> We have an engineer assigned to rewriting the ion memory driver to use >> dma_buf interfaces. Hopefully that effort will solve the problem of >> requiring these interfaces to be exported so that that driver (and others) >> can be modularized. >> >> Thanks for the reviews, drop this patch from the list and we will regroup, >> and accept that standing code in the kernel can not be modularized for the >> moment. > How is that different from the "DMA-BUF Heaps (destaging ION)" series > floating around? IDK, I am asking around because I am only superficially aware of that effort. Please view this as the left hand does not know what the right hand is doing. My issue was with a series of out-of-tree drivers that use the calls, and noted that currently the ion driver is using them as well, as rationalization for a 'user' for the export. I am pushing back on those out-of-tree drivers to switch their CMA interfaces to a modern approach as a result of these reviews; the result of this review had a positive effect because I was considering exporting them in the Android distro as a minimum, and now I am soundly rejecting that approach. Sincerely -- Mark Salyzyn
diff --git a/mm/cma.c b/mm/cma.c index 7fe0b8356775..65d830eea3b1 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -500,6 +500,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, pr_debug("%s(): returned %p\n", __func__, page); return page; } +EXPORT_SYMBOL_GPL(cma_alloc); /** * cma_release() - release allocated pages @@ -533,6 +534,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count) return true; } +EXPORT_SYMBOL_GPL(cma_release); int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data) {
Some drivers can not be turned into a module without cma_alloc and cma_release exported. Examples include ion, and we also found some out of tree infiniband and camera drivers. Signed-off-by: Mark Salyzyn <salyzyn@android.com> Cc: kernel-team@android.com Cc: linux-kernel@vger.kernel.org --- mm/cma.c | 2 ++ 1 file changed, 2 insertions(+)