shithub: dav1d

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Fix potential race condition in dav1d_get_cpu_flags()

--- a/src/cpu.c

+++ b/src/cpu.c

@@ -30,24 +30,22 @@

 #include "src/cpu.h"

+static unsigned flags = 0;

 static unsigned flags_mask = -1;

-COLD unsigned dav1d_get_cpu_flags(void) {

-    static unsigned flags;

-    static uint8_t checked = 0;

-

-    if (!checked) {

-#if (ARCH_AARCH64 || ARCH_ARM) && HAVE_ASM

-        flags = dav1d_get_cpu_flags_arm();

-#elif ARCH_PPC64LE && HAVE_ASM

-        flags = dav1d_get_cpu_flags_ppc();

-#elif ARCH_X86 && HAVE_ASM

-        flags = dav1d_get_cpu_flags_x86();

-#else

-        flags = 0;

+COLD void dav1d_init_cpu(void) {

+#if HAVE_ASM

+#if ARCH_AARCH64 || ARCH_ARM

+    flags = dav1d_get_cpu_flags_arm();

+#elif ARCH_PPC64LE

+    flags = dav1d_get_cpu_flags_ppc();

+#elif ARCH_X86

+    flags = dav1d_get_cpu_flags_x86();

 #endif

-        checked = 1;

-    }

+#endif

+}

+

+COLD unsigned dav1d_get_cpu_flags(void) {

     return flags & flags_mask;

 }

--- a/src/cpu.h

+++ b/src/cpu.h

@@ -42,7 +42,8 @@

 #include "src/x86/cpu.h"

 #endif

+void dav1d_init_cpu(void);

 unsigned dav1d_get_cpu_flags(void);

-DAV1D_API void dav1d_set_cpu_flags_mask(const unsigned mask);

+DAV1D_API void dav1d_set_cpu_flags_mask(unsigned mask);

 #endif /* DAV1D_SRC_CPU_H */

--- a/src/lib.c

+++ b/src/lib.c

@@ -37,6 +37,7 @@

 #include "common/mem.h"

 #include "common/validate.h"

+#include "src/cpu.h"

 #include "src/fg_apply.h"

 #include "src/internal.h"

 #include "src/log.h"

@@ -47,10 +48,11 @@

 #include "src/wedge.h"

 static COLD void init_internal(void) {

-    dav1d_init_wedge_masks();

+    dav1d_init_cpu();

     dav1d_init_interintra_masks();

     dav1d_init_qm_tables();

     dav1d_init_thread();

+    dav1d_init_wedge_masks();

 }

 COLD const char *dav1d_version(void) {

--- a/tests/checkasm/checkasm.c

+++ b/tests/checkasm/checkasm.c

@@ -569,6 +569,7 @@

     if (state.function_listing) {

         print_functions(state.funcs);

     } else {

+        dav1d_init_cpu();

         for (int i = 0; cpus[i].flag; i++)

             check_cpu_flag(cpus[i].name, cpus[i].flag);