Thread (10 messages) 10 messages, 4 authors, 2016-03-18

Re: [PATCH v9 2/3] kernel.h: add to_user_ptr()

From: Rob Clark <hidden>
Date: 2016-03-17 20:33:49
Also in: dri-devel, lkml

On Thu, Mar 17, 2016 at 4:22 PM, Joe Perches [off-list ref] wrote:
On Thu, 2016-03-17 at 15:43 -0300, Gustavo Padovan wrote:
quoted
2016-03-17 Gustavo Padovan [off-list ref]:
quoted
2016-03-17 Joe Perches [off-list ref]:
quoted
On Thu, 2016-03-17 at 14:30 -0300, Gustavo Padovan wrote:
quoted
This function had copies in 3 different files. Unify them in
kernel.h.
This is only used by gpu/drm.

I think this is a poor name for a generic function
that would be in kernel.h.

Isn't there an include file in linux/drm that's
appropriate for this.  Maybe drmP.h

Maybe prefix this function name with drm_ too.
No, the next patch adds a user to drivers/staging (which will be moved
to drivers/dma-buf) soon. Maybe move to a different header in
include/linux/? not sure which one.
quoted
Also, there's this that might conflict:

arch/powerpc/kernel/signal_32.c:#define to_user_ptr(p)          ptr_to_compat(p)
arch/powerpc/kernel/signal_32.c:#define to_user_ptr(p)          ((unsigned long)(p))
Right, I'll figure out how to replace these two too.
The powerpc to_user_ptr has a different meaning from the one I'm adding
in this patch. I propose we just rename powerpc's to_user_ptr to
__to_user_ptr and leave the rest as is.
I think that's not a good idea, and you should really check
this concept with the powerpc folk (added to to:s and cc:ed)

If it were really added, then the function meaning is incorrect.

This is taking a u64, casting that to (unsigned long/uint_ptr_t),
then converting that to a user pointer.

Does that naming and use make sense on x86-32 or arm32?
fwiw Gustavo's version of to_user_ptr() is in use on arm32 and arm64..
Not entirely sure what doesn't make sense about it

BR,
-R
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