From 425a5072dcd1bd895eea90a6b495392b6358ebd0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 13 Dec 2015 18:02:22 +0100 Subject: genirq: Free irq_desc with rcu The new VMD device driver needs to iterate over a list of "demultiplexing" interrupts. Protecting that list with a lock is not possible because the list is also required in code pathes which hold irq descriptor lock. Therefor the demultiplexing interrupt handler would create a lock inversion scenario if it calls a demux handler with the list protection lock held. A solution for this is to free the irq descriptor via RCU, so the list can be walked with rcu read lock held. Signed-off-by: Thomas Gleixner Cc: Keith Busch --- include/linux/irqdesc.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index a587a33363c7..dcca77c4b9d2 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -1,6 +1,8 @@ #ifndef _LINUX_IRQDESC_H #define _LINUX_IRQDESC_H +#include + /* * Core internal functions to deal with irq descriptors */ @@ -40,6 +42,7 @@ struct pt_regs; * IRQF_NO_SUSPEND set * @force_resume_depth: number of irqactions on a irq descriptor with * IRQF_FORCE_RESUME set + * @rcu: rcu head for delayed free * @dir: /proc/irq/ procfs entry * @name: flow handler name for /proc/interrupts output */ @@ -81,6 +84,9 @@ struct irq_desc { #endif #ifdef CONFIG_PROC_FS struct proc_dir_entry *dir; +#endif +#ifdef CONFIG_SPARSE_IRQ + struct rcu_head rcu; #endif int parent_irq; struct module *owner; -- cgit v1.2.3