Subject: Re: linux-next: build failure after merge of the rcu tree

From: "Paul E. McKenney" <[email-masked]>
Date: Wed, 24 Jun 2020 20:45:54 -0700

On Thu, Jun 25, 2020 at 12:57:53PM +1000, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the rcu tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
> 
> kernel/rcu/tree.c: In function 'rcu_dynticks_eqs_enter':
> kernel/rcu/tree.c:251:8: error: implicit declaration of function 'arch_atomic_add_return'; did you mean 'atomic_add_return'? [-Werror=implicit-function-declaration]
>   251 |  seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
>       |        ^~~~~~~~~~~~~~~~~~~~~~
>       |        atomic_add_return
> kernel/rcu/tree.c: In function 'rcu_dynticks_eqs_exit':
> kernel/rcu/tree.c:281:3: error: implicit declaration of function 'arch_atomic_andnot'; did you mean 'atomic_andnot'? [-Werror=implicit-function-declaration]
>   281 |   arch_atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks);
>       |   ^~~~~~~~~~~~~~~~~~
>       |   atomic_andnot
> kernel/rcu/tree.c: In function 'rcu_dynticks_curr_cpu_in_eqs':
> kernel/rcu/tree.c:314:11: error: implicit declaration of function 'arch_atomic_read'; did you mean 'atomic_read'? [-Werror=implicit-function-declaration]
>   314 |  return !(arch_atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR);
>       |           ^~~~~~~~~~~~~~~~
>       |           atomic_read
> 
> Caused by commit
> 
>   d2f8491368e5 ("rcu: Fixup noinstr warnings")
> 
> I reverted that commit for today.

MIPS doesn't much like it, either.  I hope to get an update tomorrow.

Apologies for the hassle!

							Thanx, Paul