In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_first_and_and() to avoid the need for a temporary cpumask on
the stack.

Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
---
 drivers/irqchip/irq-riscv-aplic-direct.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index 06bace9b7497..4a3ffe856d6c 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -54,15 +54,12 @@ static int aplic_direct_set_affinity(struct irq_data *d, const struct cpumask *m
 	struct aplic_direct *direct = container_of(priv, struct aplic_direct, priv);
 	struct aplic_idc *idc;
 	unsigned int cpu, val;
-	struct cpumask amask;
 	void __iomem *target;
 
-	cpumask_and(&amask, &direct->lmask, mask_val);
-
 	if (force)
-		cpu = cpumask_first(&amask);
+		cpu = cpumask_first_and(&direct->lmask, mask_val);
 	else
-		cpu = cpumask_any_and(&amask, cpu_online_mask);
+		cpu = cpumask_first_and_and(&direct->lmask, mask_val, cpu_online_mask);
 
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;
-- 
2.27.0

On Tue, Apr 16, 2024 at 2:26 PM Dawei Li <dawei.li@shingroup.cn> wrote:
>
> In general it's preferable to avoid placing cpumasks on the stack, as
> for large values of NR_CPUS these can consume significant amounts of
> stack space and make stack overflows more likely.
>
> Use cpumask_first_and_and() to avoid the need for a temporary cpumask on
> the stack.
>
> Signed-off-by: Dawei Li <dawei.li@shingroup.cn>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

> ---
>  drivers/irqchip/irq-riscv-aplic-direct.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
> index 06bace9b7497..4a3ffe856d6c 100644
> --- a/drivers/irqchip/irq-riscv-aplic-direct.c
> +++ b/drivers/irqchip/irq-riscv-aplic-direct.c
> @@ -54,15 +54,12 @@ static int aplic_direct_set_affinity(struct irq_data *d, const struct cpumask *m
>         struct aplic_direct *direct = container_of(priv, struct aplic_direct, priv);
>         struct aplic_idc *idc;
>         unsigned int cpu, val;
> -       struct cpumask amask;
>         void __iomem *target;
>
> -       cpumask_and(&amask, &direct->lmask, mask_val);
> -
>         if (force)
> -               cpu = cpumask_first(&amask);
> +               cpu = cpumask_first_and(&direct->lmask, mask_val);
>         else
> -               cpu = cpumask_any_and(&amask, cpu_online_mask);
> +               cpu = cpumask_first_and_and(&direct->lmask, mask_val, cpu_online_mask);
>
>         if (cpu >= nr_cpu_ids)
>                 return -EINVAL;
> --
> 2.27.0
>

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     5d650d1eba876717888a0951ed873ef0f1d8cf61
Gitweb:        https://git.kernel.org/tip/5d650d1eba876717888a0951ed873ef0f1d8cf61
Author:        Dawei Li <dawei.li@shingroup.cn>
AuthorDate:    Tue, 16 Apr 2024 16:54:52 +08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 24 Apr 2024 21:23:49 +02:00

irqchip/riscv-aplic-direct: Avoid explicit cpumask allocation on stack

In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_first_and_and() to avoid the need for a temporary cpumask on
the stack.

Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240416085454.3547175-6-dawei.li@shingroup.cn

---
 drivers/irqchip/irq-riscv-aplic-direct.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index 06bace9..4a3ffe8 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -54,15 +54,12 @@ static int aplic_direct_set_affinity(struct irq_data *d, const struct cpumask *m
 	struct aplic_direct *direct = container_of(priv, struct aplic_direct, priv);
 	struct aplic_idc *idc;
 	unsigned int cpu, val;
-	struct cpumask amask;
 	void __iomem *target;
 
-	cpumask_and(&amask, &direct->lmask, mask_val);
-
 	if (force)
-		cpu = cpumask_first(&amask);
+		cpu = cpumask_first_and(&direct->lmask, mask_val);
 	else
-		cpu = cpumask_any_and(&amask, cpu_online_mask);
+		cpu = cpumask_first_and_and(&direct->lmask, mask_val, cpu_online_mask);
 
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;