From fd0a68a2337b79a7bd4dad5e7d9dc726828527af Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 15 Feb 2024 19:10:01 -1000
Subject: [PATCH] workqueue, irq_work: Build fix for !CONFIG_IRQ_WORK
2f34d7337d98 ("workqueue: Fix queue_work_on() with BH workqueues") added
irq_work usage to workqueue; however, it turns out irq_work is actually
optional and the change breaks build on configuration which doesn't have
CONFIG_IRQ_WORK enabled.
Fix build by making workqueue use irq_work only when CONFIG_SMP and enabling
CONFIG_IRQ_WORK when CONFIG_SMP is set. It's reasonable to argue that it may
be better to just always enable it. However, this still saves a small bit of
memory for tiny UP configs and also the least amount of change, so, for now,
let's keep it conditional.
Verified to do the right thing for x86_64 allnoconfig and defconfig, and
aarch64 allnoconfig, allnoconfig + prink disable (SMP but nothing selects
IRQ_WORK) and a modified aarch64 Kconfig where !SMP and nothing selects
IRQ_WORK.
v2: `depends on SMP` leads to Kconfig warnings when CONFIG_IRQ_WORK is
selected by something else when !CONFIG_SMP. Use `def_bool y if SMP`
instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Fixes: 2f34d7337d98 ("workqueue: Fix queue_work_on() with BH workqueues")
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
---
init/Kconfig | 2 +-
kernel/workqueue.c | 24 +++++++++++++++---------
2 files changed, 16 insertions(+), 10 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 8df18f3a97484..0d21c9e0398f9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -106,7 +106,7 @@ config CONSTRUCTORS
bool
config IRQ_WORK
- bool
+ def_bool y if SMP
config BUILDTIME_TABLE_SORT
bool
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 04e35dbe6799d..6ae441e138047 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1209,6 +1209,20 @@ static struct irq_work *bh_pool_irq_work(struct worker_pool *pool)
return &per_cpu(bh_pool_irq_works, pool->cpu)[high];
}
+static void kick_bh_pool(struct worker_pool *pool)
+{
+#ifdef CONFIG_SMP
+ if (unlikely(pool->cpu != smp_processor_id())) {
+ irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu);
+ return;
+ }
+#endif
+ if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
+ raise_softirq_irqoff(HI_SOFTIRQ);
+ else
+ raise_softirq_irqoff(TASKLET_SOFTIRQ);
+}
+
/**
* kick_pool - wake up an idle worker if necessary
* @pool: pool to kick
@@ -1227,15 +1241,7 @@ static bool kick_pool(struct worker_pool *pool)
return false;
if (pool->flags & POOL_BH) {
- if (likely(pool->cpu == smp_processor_id())) {
- if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
- raise_softirq_irqoff(HI_SOFTIRQ);
- else
- raise_softirq_irqoff(TASKLET_SOFTIRQ);
- } else {
- irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu);
- }
-
+ kick_bh_pool(pool);
return true;
}
--
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