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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /kernel/irq/cpuhotplug.c
parentInitial commit. (diff)
downloadlinux-upstream.tar.xz
linux-upstream.zip
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/irq/cpuhotplug.c')
-rw-r--r--kernel/irq/cpuhotplug.c216
1 files changed, 216 insertions, 0 deletions
diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
new file mode 100644
index 000000000..6c7ca2e98
--- /dev/null
+++ b/kernel/irq/cpuhotplug.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic cpu hotunplug interrupt migration code copied from the
+ * arch/arm implementation
+ *
+ * Copyright (C) Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/interrupt.h>
+#include <linux/ratelimit.h>
+#include <linux/irq.h>
+
+#include "internals.h"
+
+/* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */
+static inline bool irq_needs_fixup(struct irq_data *d)
+{
+ const struct cpumask *m = irq_data_get_effective_affinity_mask(d);
+ unsigned int cpu = smp_processor_id();
+
+#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
+ /*
+ * The cpumask_empty() check is a workaround for interrupt chips,
+ * which do not implement effective affinity, but the architecture has
+ * enabled the config switch. Use the general affinity mask instead.
+ */
+ if (cpumask_empty(m))
+ m = irq_data_get_affinity_mask(d);
+
+ /*
+ * Sanity check. If the mask is not empty when excluding the outgoing
+ * CPU then it must contain at least one online CPU. The outgoing CPU
+ * has been removed from the online mask already.
+ */
+ if (cpumask_any_but(m, cpu) < nr_cpu_ids &&
+ cpumask_any_and(m, cpu_online_mask) >= nr_cpu_ids) {
+ /*
+ * If this happens then there was a missed IRQ fixup at some
+ * point. Warn about it and enforce fixup.
+ */
+ pr_warn("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n",
+ cpumask_pr_args(m), d->irq, cpu);
+ return true;
+ }
+#endif
+ return cpumask_test_cpu(cpu, m);
+}
+
+static bool migrate_one_irq(struct irq_desc *desc)
+{
+ struct irq_data *d = irq_desc_get_irq_data(desc);
+ struct irq_chip *chip = irq_data_get_irq_chip(d);
+ bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d);
+ const struct cpumask *affinity;
+ bool brokeaff = false;
+ int err;
+
+ /*
+ * IRQ chip might be already torn down, but the irq descriptor is
+ * still in the radix tree. Also if the chip has no affinity setter,
+ * nothing can be done here.
+ */
+ if (!chip || !chip->irq_set_affinity) {
+ pr_debug("IRQ %u: Unable to migrate away\n", d->irq);
+ return false;
+ }
+
+ /*
+ * No move required, if:
+ * - Interrupt is per cpu
+ * - Interrupt is not started
+ * - Affinity mask does not include this CPU.
+ *
+ * Note: Do not check desc->action as this might be a chained
+ * interrupt.
+ */
+ if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) {
+ /*
+ * If an irq move is pending, abort it if the dying CPU is
+ * the sole target.
+ */
+ irq_fixup_move_pending(desc, false);
+ return false;
+ }
+
+ /*
+ * Complete an eventually pending irq move cleanup. If this
+ * interrupt was moved in hard irq context, then the vectors need
+ * to be cleaned up. It can't wait until this interrupt actually
+ * happens and this CPU was involved.
+ */
+ irq_force_complete_move(desc);
+
+ /*
+ * If there is a setaffinity pending, then try to reuse the pending
+ * mask, so the last change of the affinity does not get lost. If
+ * there is no move pending or the pending mask does not contain
+ * any online CPU, use the current affinity mask.
+ */
+ if (irq_fixup_move_pending(desc, true))
+ affinity = irq_desc_get_pending_mask(desc);
+ else
+ affinity = irq_data_get_affinity_mask(d);
+
+ /* Mask the chip for interrupts which cannot move in process context */
+ if (maskchip && chip->irq_mask)
+ chip->irq_mask(d);
+
+ if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
+ /*
+ * If the interrupt is managed, then shut it down and leave
+ * the affinity untouched.
+ */
+ if (irqd_affinity_is_managed(d)) {
+ irqd_set_managed_shutdown(d);
+ irq_shutdown_and_deactivate(desc);
+ return false;
+ }
+ affinity = cpu_online_mask;
+ brokeaff = true;
+ }
+ /*
+ * Do not set the force argument of irq_do_set_affinity() as this
+ * disables the masking of offline CPUs from the supplied affinity
+ * mask and therefore might keep/reassign the irq to the outgoing
+ * CPU.
+ */
+ err = irq_do_set_affinity(d, affinity, false);
+ if (err) {
+ pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
+ d->irq, err);
+ brokeaff = false;
+ }
+
+ if (maskchip && chip->irq_unmask)
+ chip->irq_unmask(d);
+
+ return brokeaff;
+}
+
+/**
+ * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu
+ *
+ * The current CPU has been marked offline. Migrate IRQs off this CPU.
+ * If the affinity settings do not allow other CPUs, force them onto any
+ * available CPU.
+ *
+ * Note: we must iterate over all IRQs, whether they have an attached
+ * action structure or not, as we need to get chained interrupts too.
+ */
+void irq_migrate_all_off_this_cpu(void)
+{
+ struct irq_desc *desc;
+ unsigned int irq;
+
+ for_each_active_irq(irq) {
+ bool affinity_broken;
+
+ desc = irq_to_desc(irq);
+ raw_spin_lock(&desc->lock);
+ affinity_broken = migrate_one_irq(desc);
+ raw_spin_unlock(&desc->lock);
+
+ if (affinity_broken) {
+ pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n",
+ irq, smp_processor_id());
+ }
+ }
+}
+
+static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
+{
+ struct irq_data *data = irq_desc_get_irq_data(desc);
+ const struct cpumask *affinity = irq_data_get_affinity_mask(data);
+
+ if (!irqd_affinity_is_managed(data) || !desc->action ||
+ !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
+ return;
+
+ if (irqd_is_managed_and_shutdown(data)) {
+ irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
+ return;
+ }
+
+ /*
+ * If the interrupt can only be directed to a single target
+ * CPU then it is already assigned to a CPU in the affinity
+ * mask. No point in trying to move it around.
+ */
+ if (!irqd_is_single_target(data))
+ irq_set_affinity_locked(data, affinity, false);
+}
+
+/**
+ * irq_affinity_online_cpu - Restore affinity for managed interrupts
+ * @cpu: Upcoming CPU for which interrupts should be restored
+ */
+int irq_affinity_online_cpu(unsigned int cpu)
+{
+ struct irq_desc *desc;
+ unsigned int irq;
+
+ irq_lock_sparse();
+ for_each_active_irq(irq) {
+ desc = irq_to_desc(irq);
+ raw_spin_lock_irq(&desc->lock);
+ irq_restore_affinity_of_irq(desc, cpu);
+ raw_spin_unlock_irq(&desc->lock);
+ }
+ irq_unlock_sparse();
+
+ return 0;
+}