platform: extend nm_platform_kernel_support_get() and use atomic operations to access result

Add nm_platform_kernel_support_get_full() to allow fetching the support
state without setting it to the compile time default.

Also, use g_atomic_int_get() to access _nm_platform_kernel_support_state
values. We should not access static variables without synchronization.
Better get it correct in any case than fast.

1 files changed, 16 insertions, 6 deletions

diff --git a/src/platform/nm-platform.h b/src/platform/nm-platform.h
index f089a72783..8c9abb631a 100644
--- a/src/platform/nm-platform.h
+++ b/src/platform/nm-platform.h
@@ -986,23 +986,33 @@ _nm_platform_kernel_support_detected (NMPlatformKernelSupportType type)
 	nm_assert (   _NM_INT_NOT_NEGATIVE (type)
 	           && type < G_N_ELEMENTS (_nm_platform_kernel_support_state));
 
-	return G_LIKELY (_nm_platform_kernel_support_state[type] != 0);
+	return G_LIKELY (g_atomic_int_get (&_nm_platform_kernel_support_state[type]) != 0);
 }
 
-static inline gboolean
-nm_platform_kernel_support_get (NMPlatformKernelSupportType type)
+static inline NMTernary
+nm_platform_kernel_support_get_full (NMPlatformKernelSupportType type,
+                                     gboolean init_if_not_set)
 {
 	int v;
 
-	nm_assert (_NM_INT_NOT_NEGATIVE (type)
+	nm_assert (   _NM_INT_NOT_NEGATIVE (type)
 	           && type < G_N_ELEMENTS (_nm_platform_kernel_support_state));
 
-	v = _nm_platform_kernel_support_state[type];
-	if (G_UNLIKELY (v == 0))
+	v = g_atomic_int_get (&_nm_platform_kernel_support_state[type]);
+	if (G_UNLIKELY (v == 0)) {
+		if (!init_if_not_set)
+			return NM_TERNARY_DEFAULT;
 		v = _nm_platform_kernel_support_init (type, 0);
+	}
 	return (v >= 0);
 }
 
+static inline gboolean
+nm_platform_kernel_support_get (NMPlatformKernelSupportType type)
+{
+	return nm_platform_kernel_support_get_full (type, TRUE) != NM_TERNARY_FALSE;
+}
+
 /*****************************************************************************/
 
 struct _NMPlatformPrivate;