Re: [PATCH RFC v2 rcu 3/8] srcu: Check for consistent per-CPU per-srcu_struct NMI safety

Frederic Weisbecker
2022-10-02T22:06:29Z

On Thu, Sep 29, 2022 at 11:07:26AM -0700, Paul E. McKenney wrote:
> This commit adds runtime checks to verify that a given srcu_struct uses
> consistent NMI-safe (or not) read-side primitives on a per-CPU basis.
>
> Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: Petr Mladek <pmladek@suse.com>
> ---
> include/linux/srcu.h | 4 ++--
> include/linux/srcutiny.h | 4 ++--
> include/linux/srcutree.h | 9 +++++++--
> kernel/rcu/srcutree.c | 38 ++++++++++++++++++++++++++++++++------
> 4 files changed, 43 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/srcu.h b/include/linux/srcu.h
> index 2cc8321c0c86..565f60d57484 100644
> --- a/include/linux/srcu.h
> +++ b/include/linux/srcu.h
> @@ -180,7 +180,7 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp
> int retval;
>
> if (IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE))
> - retval = __srcu_read_lock_nmisafe(ssp);
> + retval = __srcu_read_lock_nmisafe(ssp, true);
> else
> retval = __srcu_read_lock(ssp);

Shouldn't it be checked also when CONFIG_NEED_SRCU_NMI_SAFE=n ?

Thanks.