sched_ext: Fix incorrect use of bitwise AND

[PATCH] sched_ext: Fix incorrect use of bitwise AND

Posted by Andrea Righi 2 weeks, 1 day ago

There is no reason to use a bitwise AND when checking the conditions to
enable NUMA optimization for the built-in CPU idle selection policy, so
use a logical AND instead.

Fixes: f6ce6b949304 ("sched_ext: Do not enable LLC/NUMA optimizations when domains overlap")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/lkml/20241108181753.GA2681424@thelio-3990X/
Signed-off-by: Andrea Righi <arighi@nvidia.com>
---
 kernel/sched/ext.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index f154aaeb69e4..012a7fc77263 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -3221,7 +3221,7 @@ static void update_selcpu_topology(void)
 	 * for an idle CPU in the same domain twice is redundant.
 	 */
 	cpus = cpumask_of_node(cpu_to_node(cpu));
-	if ((cpumask_weight(cpus) < num_online_cpus()) & llc_numa_mismatch())
+	if ((cpumask_weight(cpus) < num_online_cpus()) && llc_numa_mismatch())
 		enable_numa = true;
 	rcu_read_unlock();
 
-- 
2.47.0

Re: [PATCH] sched_ext: Fix incorrect use of bitwise AND

Posted by Tejun Heo 2 weeks, 1 day ago

On Fri, Nov 08, 2024 at 08:51:44PM +0100, Andrea Righi wrote:
> There is no reason to use a bitwise AND when checking the conditions to
> enable NUMA optimization for the built-in CPU idle selection policy, so
> use a logical AND instead.
> 
> Fixes: f6ce6b949304 ("sched_ext: Do not enable LLC/NUMA optimizations when domains overlap")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://lore.kernel.org/lkml/20241108181753.GA2681424@thelio-3990X/
> Signed-off-by: Andrea Righi <arighi@nvidia.com>

Applied to sched_ext/for-6.13.

Thanks.

-- 
tejun