Explain the usage of is_valid in pthread mutexes
Document the usage inside the library, and relate it with how it's
additionally used in the test code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/src/threading_helpers.c b/tests/src/threading_helpers.c
index 8cf95ee..ca91b79 100644
--- a/tests/src/threading_helpers.c
+++ b/tests/src/threading_helpers.c
@@ -70,8 +70,13 @@
* indicate the exact location of the problematic call. To locate the error,
* use a debugger and set a breakpoint on mbedtls_test_mutex_usage_error().
*/
-enum value_of_mutex_is_valid
+enum value_of_mutex_is_valid_field
{
+ /* Potential values for the is_valid field of mbedtls_threading_mutex_t.
+ * Note that MUTEX_FREED must be 0 and MUTEX_IDLE must be 1 for
+ * compatibility with threading_mutex_init_pthread() and
+ * threading_mutex_free_pthread(). MUTEX_LOCKED could be any nonzero
+ * value. */
MUTEX_FREED = 0, //!< Set by threading_mutex_free_pthread
MUTEX_IDLE = 1, //!< Set by threading_mutex_init_pthread and by our unlock
MUTEX_LOCKED = 2, //!< Set by our lock