Re: [PATCH v2 3/8] vringh: replace kmap_atomic() with kmap_local_page()

On Thu, Mar 16, 2023 at 10:13:39AM +0100, Fabio M. De Francesco wrote:

On giovedì 2 marzo 2023 12:34:16 CET Stefano Garzarella wrote:

quoted

kmap_atomic() is deprecated in favor of kmap_local_page().

With kmap_local_page() the mappings are per thread, CPU local, can take
page-faults, and can be called from any context (including interrupts).
Furthermore, the tasks can be preempted and, when they are scheduled to
run again, the kernel virtual addresses are restored and still valid.

kmap_atomic() is implemented like a kmap_local_page() which also disables
page-faults and preemption (the latter only for !PREEMPT_RT kernels,
otherwise it only disables migration).

The code within the mappings/un-mappings in getu16_iotlb() and
putu16_iotlb() don't depend on the above-mentioned side effects of
kmap_atomic(), so that mere replacements of the old API with the new one
is all that is required (i.e., there is no need to explicitly add calls
to pagefault_disable() and/or preempt_disable()).

It seems that my commit message is quite clear and complete and therefore has
already been reused by others who have somehow given me credit.

I would really appreciate it being mentioned here that you are reusing a
"boiler plate" commit message of my own making and Cc me :-)

Yes of course, sorry for not doing this previously!

Thanks,
Stefano

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