[Xen-devel] [PATCH RFC 09/35] Add cpumask_next_zero set_cpu_present and possible

[parth.dixit@xxxxxxxxxx]

From: Naresh Bhat <naresh.bhat@xxxxxxxxxx>

Introduce and use cpumask_next_zero, set_cpu_present and set_cpu_possible.

Signed-off-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
---
 xen/common/cpu.c          | 18 ++++++++++++++++++
 xen/include/xen/cpumask.h | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/xen/common/cpu.c b/xen/common/cpu.c
index 630881e..da399c9 100644
--- a/xen/common/cpu.c
+++ b/xen/common/cpu.c
@@ -216,3 +216,21 @@ void enable_nonboot_cpus(void)
 
     cpumask_clear(&frozen_cpus);
 }
+
+static DECLARE_BITMAP(cpu_present_bits, NR_CPUS) __read_mostly;
+static DECLARE_BITMAP(cpu_possible_bits, NR_CPUS) __read_mostly;
+void set_cpu_possible(unsigned int cpu, bool possible)
+{
+    if ( possible )
+         cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
+    else
+        cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
+}
+
+void set_cpu_present(unsigned int cpu, bool present)
+{
+    if ( present )
+        cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
+    else
+        cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
+}
diff --git a/xen/include/xen/cpumask.h b/xen/include/xen/cpumask.h
index 850b4a2..209483e 100644
--- a/xen/include/xen/cpumask.h
+++ b/xen/include/xen/cpumask.h
@@ -78,6 +78,7 @@
 #include <xen/bitmap.h>
 #include <xen/kernel.h>
 #include <xen/random.h>
+#include <xen/stdbool.h>
 
 typedef struct cpumask{ DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
 
@@ -295,6 +296,22 @@ static inline int cpulist_scnprintf(char *buf, int len,
 }
 
 /*
+ * cpumask_next_zero - get the next unset cpu in a cpumask
+ * @n: the cpu prior to the place to search (ie. return will be > @n)
+ * @srcp: the cpumask pointer
+ *
+ * Returns >= nr_cpu_ids if no further cpus unset.
+ */
+static inline unsigned int cpumask_next_zero(int n, const cpumask_t *srcp)
+{
+    /* -1 is a legal arg here. */
+    if (n != -1)
+        cpumask_check(n);
+
+    return find_next_zero_bit(srcp->bits, nr_cpu_ids, n+1);
+}
+
+/*
  * cpumask_var_t: struct cpumask for stack usage.
  *
  * Oh, the wicked games we play!  In order to make kernel coding a
@@ -440,6 +457,29 @@ extern cpumask_t cpu_present_map;
 #define for_each_online_cpu(cpu)   for_each_cpu(cpu, &cpu_online_map)
 #define for_each_present_cpu(cpu)  for_each_cpu(cpu, &cpu_present_map)
 
+/* Wrappers for arch boot code to manipulate normally-constant masks */
+void set_cpu_possible(unsigned int cpu, bool possible);
+void set_cpu_present(unsigned int cpu, bool present);
+
+/*
+ * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask *
+ * @bitmap: the bitmap
+ *
+ * There are a few places where cpumask_var_t isn't appropriate and
+ * static cpumasks must be used (eg. very early boot), yet we don't
+ * expose the definition of 'struct cpumask'.
+ *
+ * This does the conversion, and can be used as a constant initializer.
+ */
+#define to_cpumask(bitmap)                                              \
+        ((struct cpumask *)(1 ? (bitmap)                                \
+                            : (void *)sizeof(__check_is_bitmap(bitmap))))
+
+static inline int __check_is_bitmap(const unsigned long *bitmap)
+{
+    return 1;
+}
+
 /* Copy to/from cpumap provided by control tools. */
 struct xenctl_bitmap;
 int cpumask_to_xenctl_bitmap(struct xenctl_bitmap *, const cpumask_t *);
-- 
1.9.1


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