Re: [PATCH 02/10] rcu: Move rcu_preempt_depth_set() to rcupdate.h

[Joel Fernandes]

> On Mar 28, 2024, at 1:20 PM, Lai Jiangshan <jiangshanlai@xxxxxxxxx> wrote:
> 
> From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
> 
> Prepare for arch-specific-defined rcu_preempt_depth_set().
> 
> No functionality change intended, but it has to be defined as a macro
> as rcupdate.h is a very low level header included from areas that don't
> even know about the task struct "current".

Sorry I did not follow changelog. If some rcupdate.h includers do not know
about task_struct, how does adding a macro that uses current help?

Thanks,

 - Joel

> 
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
> Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
> ---
> include/linux/rcupdate.h | 1 +
> kernel/rcu/tree_plugin.h | 5 -----
> 2 files changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 16f519914415..210f65baf47c 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -78,6 +78,7 @@ void __rcu_read_unlock(void);
>  * types of kernel builds, the rcu_read_lock() nesting depth is unknowable.
>  */
> #define rcu_preempt_depth() READ_ONCE(current->rcu_read_lock_nesting)
> +#define rcu_preempt_depth_set(val) WRITE_ONCE(current->rcu_read_lock_nesting, (val))
> 
> #else /* #ifdef CONFIG_PREEMPT_RCU */
> 
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 36a8b5dbf5b5..b1264096d03a 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -387,11 +387,6 @@ static int rcu_preempt_read_exit(void)
>    return ret;
> }
> 
> -static void rcu_preempt_depth_set(int val)
> -{
> -    WRITE_ONCE(current->rcu_read_lock_nesting, val);
> -}
> -
> /*
>  * Preemptible RCU implementation for rcu_read_lock().
>  * Just increment ->rcu_read_lock_nesting, shared state will be updated
> --
> 2.19.1.6.gb485710b
>