[tip:irq/core] genirq/affinity: Introduce struct irq_affinity

[tip-bot for Christoph Hellwig <tipbot@zytor.com>]

Commit-ID:  20e407e195b29a4f5a18d713a61f54a75f992bd5
Gitweb:     http://git.kernel.org/tip/20e407e195b29a4f5a18d713a61f54a75f992bd5
Author:     Christoph Hellwig <hch@lst.de>
AuthorDate: Tue, 8 Nov 2016 17:15:01 -0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 9 Nov 2016 08:25:08 +0100

genirq/affinity: Introduce struct irq_affinity

Some drivers (various network and RDMA adapter for example) have a MSI-X
vector layout where most of the vectors are used for I/O queues and should
have CPU affinity assigned to them, but some (usually 1 but sometimes more)
at the beginning or end are used for low-performance admin or configuration
work and should not have any explicit affinity assigned to them.

Add a new irq_affinity structure, which will be passed through a variant of
pci_irq_alloc_vectors that allows to specify these requirements (and is
extensible to any future quirks in that area) so that the core IRQ affinity
algorithm can take this quirks into account.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Link: http://lkml.kernel.org/r/1478654107-7384-2-git-send-email-hch@lst.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 include/linux/interrupt.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 72f0721..6b52686 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -232,6 +232,18 @@ struct irq_affinity_notify {
 	void (*release)(struct kref *ref);
 };
 
+/**
+ * struct irq_affinity - Description for automatic irq affinity assignements
+ * @pre_vectors:	Don't apply affinity to @pre_vectors at beginning of
+ *			the MSI(-X) vector space
+ * @post_vectors:	Don't apply affinity to @post_vectors at end of
+ *			the MSI(-X) vector space
+ */
+struct irq_affinity {
+	int	pre_vectors;
+	int	post_vectors;
+};
+
 #if defined(CONFIG_SMP)
 
 extern cpumask_var_t irq_default_affinity;