#define PER_CPU_MEM_SIZE 4096
extern int __num_possible_cpus;
+
+#define LTTNG_UST_CPUMASK_SIZE 4096
+
+/*
+ * Get the CPU possible mask string from sysfs.
+ *
+ * buf: the buffer where the mask will be read.
+ * max_bytes: the maximum number of bytes to write in the buffer.
+ *
+ * Returns the number of bytes read or -1 on error.
+ */
+int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
+ __attribute__((visibility("hidden")));
+
+/*
+ * Get the number of possible CPUs in the system from either
+ * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc.
+ *
+ * Returns the number of possible CPUs in the system or 0 on error.
+ */
+int get_num_possible_cpus_fallback(void)
+ __attribute__((visibility("hidden")));
+
+/*
+ * Get the number of CPUs from the possible cpu mask.
+ *
+ * pmask: the mask to parse.
+ * len: the len of the mask excluding '\0'.
+ *
+ * Returns the number of possible CPUs from the mask or 0 on error.
+ */
+int get_num_possible_cpus_from_mask(const char *pmask, size_t len)
+ __attribute__((visibility("hidden")));
+
extern void _get_num_possible_cpus(void);
+/*
+ * Returns the total number of CPUs in the system. If the cache is not yet
+ * initialized, get the value from "/sys/devices/system/cpu/possible" or
+ * fallback to sysconf and cache it.
+ *
+ * If all methods fail, don't populate the cache and return 0.
+ */
static inline
int num_possible_cpus(void)
{
- if (!__num_possible_cpus)
+ if (caa_unlikely(!__num_possible_cpus))
_get_num_possible_cpus();
+
return __num_possible_cpus;
}