On Sun, 06 May 2018 07:57:27 PDT (-0700), mi...@kernel.org wrote:
>
> * Andrea Parri <andrea.pa...@amarulasolutions.com> wrote:
>
>> Hi Ingo,
>>
>> > From 5affbf7e91901143f84f1b2ca64f4afe70e210fd Mon Sep 17 00:00:00 2001
>> > From: Ingo Molnar <mi...@kernel.org>
>> > Date: Sat, 5 May 2018 10:23:23 +0200
>> > Subject: [PATCH] locking/atomics: Simplify the op definitions in atomic.h
>> > some more
>> >
>> > Before:
>> >
>> > #ifndef atomic_fetch_dec_relaxed
>> > # ifndef atomic_fetch_dec
>> > # define atomic_fetch_dec(v) atomic_fetch_sub(1, (v))
>> > # define atomic_fetch_dec_relaxed(v)
>> > atomic_fetch_sub_relaxed(1, (v))
>> > # define atomic_fetch_dec_acquire(v)
>> > atomic_fetch_sub_acquire(1, (v))
>> > # define atomic_fetch_dec_release(v)
>> > atomic_fetch_sub_release(1, (v))
>> > # else
>> > # define atomic_fetch_dec_relaxed atomic_fetch_dec
>> > # define atomic_fetch_dec_acquire atomic_fetch_dec
>> > # define atomic_fetch_dec_release atomic_fetch_dec
>> > # endif
>> > #else
>> > # ifndef atomic_fetch_dec_acquire
>> > # define atomic_fetch_dec_acquire(...)
>> > __atomic_op_acquire(atomic_fetch_dec, __VA_ARGS__)
>> > # endif
>> > # ifndef atomic_fetch_dec_release
>> > # define atomic_fetch_dec_release(...)
>> > __atomic_op_release(atomic_fetch_dec, __VA_ARGS__)
>> > # endif
>> > # ifndef atomic_fetch_dec
>> > # define atomic_fetch_dec(...)
>> > __atomic_op_fence(atomic_fetch_dec, __VA_ARGS__)
>> > # endif
>> > #endif
>> >
>> > After:
>> >
>> > #ifndef atomic_fetch_dec_relaxed
>> > # ifndef atomic_fetch_dec
>> > # define atomic_fetch_dec(v) atomic_fetch_sub(1, (v))
>> > # define atomic_fetch_dec_relaxed(v)
>> > atomic_fetch_sub_relaxed(1, (v))
>> > # define atomic_fetch_dec_acquire(v)
>> > atomic_fetch_sub_acquire(1, (v))
>> > # define atomic_fetch_dec_release(v)
>> > atomic_fetch_sub_release(1, (v))
>> > # else
>> > # define atomic_fetch_dec_relaxed atomic_fetch_dec
>> > # define atomic_fetch_dec_acquire atomic_fetch_dec
>> > # define atomic_fetch_dec_release atomic_fetch_dec
>> > # endif
>> > #else
>> > # ifndef atomic_fetch_dec
>> > # define atomic_fetch_dec(...)
>> > __atomic_op_fence(atomic_fetch_dec, __VA_ARGS__)
>> > # define atomic_fetch_dec_acquire(...)
>> > __atomic_op_acquire(atomic_fetch_dec, __VA_ARGS__)
>> > # define atomic_fetch_dec_release(...)
>> > __atomic_op_release(atomic_fetch_dec, __VA_ARGS__)
>> > # endif
>> > #endif
>> >
>> > The idea is that because we already group these APIs by certain defines
>> > such as atomic_fetch_dec_relaxed and atomic_fetch_dec in the primary
>> > branches - we can do the same in the secondary branch as well.
>> >
>> > ( Also remove some unnecessarily duplicate comments, as the API
>> > group defines are now pretty much self-documenting. )
>> >
>> > No change in functionality.
>> >
>> > Cc: Peter Zijlstra <pet...@infradead.org>
>> > Cc: Linus Torvalds <torva...@linux-foundation.org>
>> > Cc: Andrew Morton <a...@linux-foundation.org>
>> > Cc: Thomas Gleixner <t...@linutronix.de>
>> > Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
>> > Cc: Will Deacon <will.dea...@arm.com>
>> > Cc: linux-kernel@vger.kernel.org
>> > Signed-off-by: Ingo Molnar <mi...@kernel.org>
>>
>> This breaks compilation on RISC-V. (For some of its atomics, the arch
>> currently defines the _relaxed and the full variants and it relies on
>> the generic definitions for the _acquire and the _release variants.)
>
> I don't have cross-compilation for RISC-V, which is a relatively new arch.
> (Is there any RISC-V set of cross-compilation tools on kernel.org somewhere?)
Arnd added RISC-V to the cross compiler list a month or two ago when he updated
them all. I use the "make.cross" script from the Intel test robot, which will
fetch the cross compilers for you. It looks like I made a Git Hub pull request
to update the script for RISC-V, it fetches from kernel.org
https://github.com/palmer-dabbelt/lkp-tests/blob/e14f4236ccd0572f4b87ffd480fecefee412dedc/sbin/make.cross
http://cdn.kernel.org/pub/tools/crosstool/files/bin/
http://cdn.kernel.org/pub/tools/crosstool/files/bin/x86_64/7.3.0/x86_64-gcc-7.3.0-nolibc_riscv64-linux.tar.gz
> Could you please send a patch that defines those variants against Linus's
> tree,
> like the PowerPC patch that does something similar:
>
> 0476a632cb3a: locking/atomics/powerpc: Move cmpxchg helpers to
> asm/cmpxchg.h and define the full set of cmpxchg APIs
>
> ?
>
> ... and I'll integrate it into the proper place to make it all bisectable,
> etc.
Sorry, I got buried in email again. Did this get merged, or is there a current
version of the patch set I should look at?
