[PATCH] kernel/irq: Make irq_set_affinity_hint return the real return value

[PATCH] kernel/irq: Make irq_set_affinity_hint return the real return value

[Hao Peng]

irq_set_affinity_hint does not return the return value of
__irq_set_affinity, which makes the state of functions dependent
on the return value of irq_set_affinity_hint inconsistent.

Signed-off-by: Peng Hao <flyingpeng@tencent.com>
---
 kernel/irq/manage.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index ef30b4762947..86196fb826d6 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -490,6 +490,7 @@ EXPORT_SYMBOL_GPL(irq_force_affinity);
 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 {
        unsigned long flags;
+       int ret = 0;
        struct irq_desc *desc = irq_get_desc_lock(irq, &flags,
IRQ_GET_DESC_CHECK_GLOBAL);

        if (!desc)
@@ -498,8 +499,8 @@ int irq_set_affinity_hint(unsigned int irq, const
struct cpumask *m)
        irq_put_desc_unlock(desc, flags);
        /* set the initial affinity to prevent every interrupt being on CPU0 */
        if (m)
-               __irq_set_affinity(irq, m, false);
-       return 0;
+               ret = __irq_set_affinity(irq, m, false);
+       return ret;
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);

--
2.27.0

Re: [PATCH] kernel/irq: Make irq_set_affinity_hint return the real return value

[Thomas Gleixner]

On Mon, Sep 06 2021 at 16:20, Hao Peng wrote:
> irq_set_affinity_hint does not return the return value of
> __irq_set_affinity, which makes the state of functions dependent
> on the return value of irq_set_affinity_hint inconsistent.

No, it does not. The affinity hint has been installed even in the case
that __irq_set_affinity() fails.

Setting the affinity in that function is a best effort operation without
any guarantees and in hindsight this should have never been added to
this function.

Thanks,

        tglx