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authorThomas Gleixner <tglx@linutronix.de>2010-09-27 11:48:26 -0400
committerThomas Gleixner <tglx@linutronix.de>2010-10-12 10:39:07 -0400
commit1f5a5b87f78fade3ae48dfd55e8765d1d622ea4e (patch)
tree762a5dbf40129ffd9667a170b2503a77c95320f7 /include/linux/irq.h
parent1318a481fc37c503a901b96ae06b692ca2b21af5 (diff)
genirq: Implement a sane sparse_irq allocator
The current sparse_irq allocator has several short comings due to failures in the design or the lack of it: - Requires iteration over the number of active irqs to find a free slot (Some architectures have grown their own workarounds for this) - Removal of entries is not possible - Racy between create_irq_nr and destroy_irq (plugged by horrible callbacks) - Migration of active irq descriptors is not possible - No bulk allocation of irq ranges - Sprinkeled irq_desc references all over the place outside of kernel/irq/ (The previous chip functions series is addressing this issue) Implement a sane allocator which fixes the above short comings (though migration of active descriptors needs a full tree wide cleanup of the direct and mostly unlocked access to irq_desc). The new allocator still uses a radix_tree, but uses a bitmap for keeping track of allocated irq numbers. That allows: - Fast lookup of a free slot - Allows the removal of descriptors - Prevents the create/destroy race - Bulk allocation of consecutive irq ranges - Basic design is ready for migration of life descriptors after further cleanups The bitmap is also used in the SPARSE_IRQ=n case for lookup and raceless (de)allocation of irq numbers. So it removes the requirement for looping through the descriptor array to find slots. Right now it uses sparse_irq_lock to protect the bitmap and the radix tree, but after cleaning up all users we should be able convert that to a mutex and to switch the radix_tree and decriptor allocations to GFP_KERNEL. [ Folded in a bugfix from Yinghai Lu ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/irq.h')
-rw-r--r--include/linux/irq.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 30a300991ed4..cefacf928b33 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -398,6 +398,29 @@ static inline struct irq_2_iommu *irq_data_get_iommu(struct irq_data *d)
398} 398}
399#endif 399#endif
400 400
401int irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node);
402void irq_free_descs(unsigned int irq, unsigned int cnt);
403
404static inline int irq_alloc_desc(int node)
405{
406 return irq_alloc_descs(-1, 0, 1, node);
407}
408
409static inline int irq_alloc_desc_at(unsigned int at, int node)
410{
411 return irq_alloc_descs(at, at, 1, node);
412}
413
414static inline int irq_alloc_desc_from(unsigned int from, int node)
415{
416 return irq_alloc_descs(-1, from, 1, node);
417}
418
419static inline void irq_free_desc(unsigned int irq)
420{
421 irq_free_descs(irq, 1);
422}
423
401#endif /* CONFIG_GENERIC_HARDIRQS */ 424#endif /* CONFIG_GENERIC_HARDIRQS */
402 425
403#endif /* !CONFIG_S390 */ 426#endif /* !CONFIG_S390 */