Am 02.07.24 um 08:40 schrieb Christoph Hellwig:

On Mon, Jul 01, 2024 at 11:26:34PM -0700, Andrew Morton wrote:

...

No, I do think the cast is useful:

struct page *page = dma_fence_chain_alloc();

will presently generate a warning. We want this. Your change will remove that useful warning.

Unrelatedly: there is no earthly reason why this is implemented as a macro. A static inline function would be so much better. Why do we keep doing this.

Agreed with all of the above. Adding the dmabuf maintainers.

Thanks for adding me and I have to ask to be added on DMA-buf patches when initially sending them out.

First of all: Yes that cast is intentionally there and yes that is intentionally a define and not an inline function.

See this patch here which changed that:

commit 2c321f3f70bc284510598f712b702ce8d60c4d14 Author: Suren Baghdasaryan surenb@google.com Date:   Sun Apr 14 19:07:31 2024 -0700

mm: change inlined allocation helpers to account at the call site

Main goal of memory allocation profiling patchset is to provide accounting     that is cheap enough to run in production.  To achieve that we inject     counters using codetags at the allocation call sites to account every time     allocation is made.  This injection allows us to perform accounting     efficiently because injected counters are immediately available as opposed     to the alternative methods, such as using _RET_IP_, which would require     counter lookup and appropriate locking that makes accounting much more     expensive.  This method requires all allocation functions to inject     separate counters at their call sites so that their callers can be     individually accounted.  Counter injection is implemented by allocation     hooks which should wrap all allocation functions.

Inlined functions which perform allocations but do not use allocation     hooks are directly charged for the allocations they perform.  In most     cases these functions are just specialized allocation wrappers used from     multiple places to allocate objects of a specific type.  It would be more     useful to do the accounting at their call sites instead. Instrument these     helpers to do accounting at the call site.  Simple inlined allocation     wrappers are converted directly into macros.  More complex allocators or     allocators with documentation are converted into _noprof versions and     allocation hooks are added.  This allows memory allocation profiling     mechanism to charge allocations to the callers of these functions.

Regards, Christian.