Relicense common/smp.c common/smp.h to MIT

[lttng-ust.git] / src / common / smp.h

diff --git a/src/common/smp.h b/src/common/smp.h
index 51fbd2d7e5d34c01c04df7d13ac4397302a223c0..5f77ebd137971acf64f738261499ecd8d228a62e 100644 (file)
--- a/src/common/smp.h
+++ b/src/common/smp.h
@@ -1,5 +1,5 @@
 /*
- * SPDX-License-Identifier: LGPL-2.1-only
+ * SPDX-License-Identifier: MIT
  *
  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
@@ -9,6 +9,18 @@
 
 #define LTTNG_UST_CPUMASK_SIZE 4096
 
+/*
+ * Get a CPU 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.
+ * path: file path to read the mask from.
+ *
+ * Returns the number of bytes read or -1 on error.
+ */
+int get_cpu_mask_from_sysfs(char *buf, size_t max_bytes, const char *path)
+       __attribute__((visibility("hidden")));
+
 /*
  * Get the CPU possible mask string from sysfs.
  *
@@ -20,6 +32,21 @@
 int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
        __attribute__((visibility("hidden")));
 
+/*
+ * Get the highest CPU id from sysfs.
+ *
+ * Iterate on all the folders in "/sys/devices/system/cpu" that start with
+ * "cpu" followed by an integer, keep the highest CPU id encountered during
+ * this iteration and add 1 to get a number of CPUs.
+ *
+ * Returns the highest CPU id, or -1 on error.
+ */
+int get_max_cpuid_from_sysfs(void)
+       __attribute__((visibility("hidden")));
+
+int _get_max_cpuid_from_sysfs(const char *path)
+       __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.
@@ -30,27 +57,31 @@ int get_num_possible_cpus_fallback(void)
        __attribute__((visibility("hidden")));
 
 /*
- * Get the number of CPUs from the possible cpu mask.
+ * Get the highest CPU id from a 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.
+ * Returns the highest CPU id from the mask or -1 on error.
  */
-int get_num_possible_cpus_from_mask(const char *pmask, size_t len)
+int get_max_cpuid_from_mask(const char *pmask, size_t len)
        __attribute__((visibility("hidden")));
 
 /*
- * 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.
+ * Returns the length of an array that could contain a per-CPU element for each
+ * possible CPU id for the lifetime of the process.
+ *
+ * We currently assume CPU ids are contiguous up the maximum CPU id.
+ *
+ * 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.
  */
-int num_possible_cpus(void)
+int get_possible_cpus_array_len(void)
        __attribute__((visibility("hidden")));
 
 #define for_each_possible_cpu(cpu)             \
-       for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)
+       for ((cpu) = 0; (cpu) < get_possible_cpus_array_len(); (cpu)++)
 
 #endif /* _UST_COMMON_SMP_H */