On Thu, Aug 22, 2024 at 11:21:28AM +0800, Zhen Lei wrote:
> The value of ARRAY_SIZE() can be determined at compile time, so if both
> sides of the equation are ARRAY_SIZE(), using BUILD_BUG_ON() can help us
> catch the problem earlier.
>
> While there are cases where unequal array sizes will work, there is no
> point in allowing them, so it makes more sense to force them to be equal
> using BUILD_BUG_ON().
>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> ---
> kernel/rcu/srcutree.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index b24db425f16d850..a9c7795bb77d650 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -128,7 +128,7 @@ static void init_srcu_struct_data(struct srcu_struct *ssp)
> * Initialize the per-CPU srcu_data array, which feeds into the
> * leaves of the srcu_node tree.
> */
> - WARN_ON_ONCE(ARRAY_SIZE(sdp->srcu_lock_count) !=
> + BUILD_BUG_ON(ARRAY_SIZE(sdp->srcu_lock_count) !=
> ARRAY_SIZE(sdp->srcu_unlock_count));
> for_each_possible_cpu(cpu) {
> sdp = per_cpu_ptr(ssp->sda, cpu);
> @@ -186,7 +186,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags)
> /* Each pass through this loop initializes one srcu_node structure. */
> srcu_for_each_node_breadth_first(ssp, snp) {
> spin_lock_init(&ACCESS_PRIVATE(snp, lock));
> - WARN_ON_ONCE(ARRAY_SIZE(snp->srcu_have_cbs) !=
> + BUILD_BUG_ON(ARRAY_SIZE(snp->srcu_have_cbs) !=
> ARRAY_SIZE(snp->srcu_data_have_cbs));
> for (i = 0; i < ARRAY_SIZE(snp->srcu_have_cbs); i++) {
> snp->srcu_have_cbs[i] = SRCU_SNP_INIT_SEQ;
> --
> 2.34.1
>
