Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

06efc7df · Linus Torvalds <[email protected]> · 2017-07-30 11:27:33 -07:00

Pull irq fix from Thomas Gleixner:
 "Fix for a regression caused by the conversion of x86 to the generic
  hotplug code.

  Instead of doing a plain single line revert, this adds a pile of
  comments so the semantics of the force argument are clear"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/cpuhotplug: Revert "Set force affinity flag on hotplug migration"

Commit: 06efc7df376659963ba4de26217ebdcdc2a6c09b
Parents: 0a07b238 · 83979133

Merge commit. Changes below are compared with the first parent: 0a07b238.

Changes

2 files changed · +13 −3

File	Status	Add	Del	Content
include/linux/irq.h	modified	+6	−1	View file
kernel/irq/cpuhotplug.c	modified	+7	−2	View file

include/linux/irq.h

View file

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 00db35b..d2d5437 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -388,7 +388,12 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
  * @irq_mask_ack:	ack and mask an interrupt source
  * @irq_unmask:		unmask an interrupt source
  * @irq_eoi:		end of interrupt
- * @irq_set_affinity:	set the CPU affinity on SMP machines
+ * @irq_set_affinity:	Set the CPU affinity on SMP machines. If the force
+ *			argument is true, it tells the driver to
+ *			unconditionally apply the affinity setting. Sanity
+ *			checks against the supplied affinity mask are not
+ *			required. This is used for CPU hotplug where the
+ *			target CPU is not yet set in the cpu_online_mask.
  * @irq_retrigger:	resend an IRQ to the CPU
  * @irq_set_type:	set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ
  * @irq_set_wake:	enable/disable power-management wake-on of an IRQ

kernel/irq/cpuhotplug.c

View file

diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
index aee8f7e..638eb9c 100644
--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -95,8 +95,13 @@ static bool migrate_one_irq(struct irq_desc *desc)
 		affinity = cpu_online_mask;
 		brokeaff = true;
 	}
-
-	err = irq_do_set_affinity(d, affinity, 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);