Re: [RFC v2 PATCH 03/14] irq: add new struct ipi_mask

From: Qais Yousef
Date: Tue Oct 13 2015 - 10:26:35 EST


On 10/13/2015 02:26 PM, Thomas Gleixner wrote:
On Tue, 13 Oct 2015, Qais Yousef wrote:
cpumask is limited to NR_CPUS. introduce ipi_mask which allows us to address
cpu range that is higher than NR_CPUS which is required for drivers to send
IPIs for coprocessor that are outside Linux CPU range.

Signed-off-by: Qais Yousef <qais.yousef@xxxxxxxxxx>
---
include/linux/irq.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 11bf09288ddb..4b537e4d393b 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -125,6 +125,21 @@ enum {
struct msi_desc;
struct irq_domain;
+ /**
+ * struct ipi_mask - IPI mask information
+ * @cpumask: bitmap of cpumasks
+ * @nbits: number of bits in cpumask
+ * @global: whether the mask is SMP IPI ie: subset of cpu_possible_mask or not
+ *
+ * ipi_mask is similar to cpumask, but it provides nbits that's configurable
+ * rather than fixed to NR_CPUS.
+ */
+struct ipi_mask {
+ unsigned long *cpumask;
+ unsigned int nbits;
+ bool global;
+};
Can you make that:

struct ipi_mask {
unsigned int nbits;
bool global;
unsigned long cpu_bitmap[];
};

That allows you to allocate the data structure in one go. So the
ipi_mask in irq_data_common becomes a pointer which is only filled in
when ipi_mask is actually used.

Note, I renamed cpumask to cpu_bitmap to avoid confusion with
cpumasks.

We also want a helper function

struct cpumask *irq_data_get_ipi_mask(struct irq_data *data);

so we can use normal cpumask operations for the majority of cases.



Will do.

Thanks,
Qais
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