path: root/kernel/irq
diff options
authorThomas Gleixner <>2015-07-05 17:12:30 +0000
committerThomas Gleixner <>2015-07-08 11:32:25 +0200
commita899418167264c7bac574b1a0f1b2c26c5b0995a (patch)
tree92d1185f96f4ed72643cce403ab007a12bbbd7fc /kernel/irq
parentd770e558e21961ad6cfdf0ff7df0eb5d7d4f0754 (diff)
hotplug: Prevent alloc/free of irq descriptors during cpu up/down
When a cpu goes up some architectures (e.g. x86) have to walk the irq space to set up the vector space for the cpu. While this needs extra protection at the architecture level we can avoid a few race conditions by preventing the concurrent allocation/free of irq descriptors and the associated data. When a cpu goes down it moves the interrupts which are targeted to this cpu away by reassigning the affinities. While this happens interrupts can be allocated and freed, which opens a can of race conditions in the code which reassignes the affinities because interrupt descriptors might be freed underneath. Example: CPU1 CPU2 cpu_up/down irq_desc = irq_to_desc(irq); remove_from_radix_tree(desc); raw_spin_lock(&desc->lock); free(desc); We could protect the irq descriptors with RCU, but that would require a full tree change of all accesses to interrupt descriptors. But fortunately these kind of race conditions are rather limited to a few things like cpu hotplug. The normal setup/teardown is very well serialized. So the simpler and obvious solution is: Prevent allocation and freeing of interrupt descriptors accross cpu hotplug. Signed-off-by: Thomas Gleixner <> Acked-by: Peter Zijlstra <> Cc: xiao jin <> Cc: Joerg Roedel <> Cc: Borislav Petkov <> Cc: Yanmin Zhang <> Link:
Diffstat (limited to 'kernel/irq')
1 files changed, 0 insertions, 4 deletions
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 4834ee828c41..61008b8433ab 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -76,12 +76,8 @@ extern void unmask_threaded_irq(struct irq_desc *desc);
static inline void irq_mark_irq(unsigned int irq) { }
-extern void irq_lock_sparse(void);
-extern void irq_unlock_sparse(void);
extern void irq_mark_irq(unsigned int irq);
-static inline void irq_lock_sparse(void) { }
-static inline void irq_unlock_sparse(void) { }
extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);