[igt-dev] [PATCH i-g-t v3 3/4] i915/gem_create: use atomic_* instead of __sync_*

[Guillaume Tucker]

This fixes builds on some architectures, in particular MIPS which
doesn't have __sync_add_and_fetch_8 and __sync_val_compare_and_swap_8
for 64-bit variable handling.

* replace calls to the older __sync_* functions with the new atomic_*
  standard ones
* use the _Atomic type modifier as required with stdatomic.h functions
* add dependency for gem_create on libatomic

Signed-off-by: Guillaume Tucker <guillaume.tucker at collabora.com>
Reviewed-by: Simon Ser <simon.ser at intel.com>
---

Notes:
    v2: use atomic_* and only link libatomic with gem_create

 tests/Makefile.am       |  2 +-
 tests/i915/gem_create.c | 16 ++++++++++++----
 tests/meson.build       |  9 ++++++++-
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 5a428b8ac213..bbd386c9c2db 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -90,7 +90,7 @@ AM_LDFLAGS = -Wl,--as-needed
 drm_import_export_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
 drm_import_export_LDADD = $(LDADD) -lpthread
 gem_create_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
-gem_create_LDADD = $(LDADD) -lpthread
+gem_create_LDADD = $(LDADD) -lpthread -latomic
 gem_close_race_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
 gem_close_race_LDADD = $(LDADD) -lpthread
 gem_ctx_thrash_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
diff --git a/tests/i915/gem_create.c b/tests/i915/gem_create.c
index 43cbf45f289b..9008cd8a21e3 100644
--- a/tests/i915/gem_create.c
+++ b/tests/i915/gem_create.c
@@ -45,6 +45,7 @@
 #include <sys/time.h>
 #include <getopt.h>
 #include <pthread.h>
+#include <stdatomic.h>
 
 #include <drm.h>
 
@@ -156,7 +157,14 @@ static void invalid_nonaligned_size(int fd)
 	gem_close(fd, create.handle);
 }
 
-static uint64_t get_npages(uint64_t *global, uint64_t npages)
+static uint64_t atomic_compare_swap_u64(_Atomic(uint64_t) *ptr,
+					uint64_t oldval, uint64_t newval)
+{
+	atomic_compare_exchange_strong(ptr, &oldval, newval);
+	return oldval;
+}
+
+static uint64_t get_npages(_Atomic(uint64_t) *global, uint64_t npages)
 {
 	uint64_t try, old, max;
 
@@ -165,13 +173,13 @@ static uint64_t get_npages(uint64_t *global, uint64_t npages)
 		old = max;
 		try = 1 + npages % (max / 2);
 		max -= try;
-	} while ((max = __sync_val_compare_and_swap(global, old, max)) != old);
+	} while ((max = atomic_compare_swap_u64(global, old, max)) != old);
 
 	return try;
 }
 
 struct thread_clear {
-	uint64_t max;
+	_Atomic(uint64_t) max;
 	int timeout;
 	int i915;
 };
@@ -202,7 +210,7 @@ static void *thread_clear(void *data)
 		}
 		gem_close(i915, create.handle);
 
-		__sync_add_and_fetch(&arg->max, npages);
+		atomic_fetch_add(&arg->max, npages);
 	}
 
 	return NULL;
diff --git a/tests/meson.build b/tests/meson.build
index f168fbbae2a8..ffd432d38193 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -110,7 +110,6 @@ i915_progs = [
 	'gem_close_race',
 	'gem_concurrent_blit',
 	'gem_cpu_reloc',
-	'gem_create',
 	'gem_cs_prefetch',
 	'gem_cs_tlb',
 	'gem_ctx_bad_destroy',
@@ -277,6 +276,14 @@ foreach prog : i915_progs
 	test_list += prog
 endforeach
 
+test_executables += executable('gem_create',
+	   join_paths('i915', 'gem_create.c'),
+	   dependencies : test_deps + [ libatomic ],
+	   install_dir : libexecdir,
+	   install_rpath : libexecdir_rpathdir,
+	   install : true)
+test_list += 'gem_create'
+
 test_executables += executable('gem_ctx_sseu',
 	   join_paths('i915', 'gem_ctx_sseu.c'),
 	   dependencies : test_deps + [ lib_igt_perf ],
-- 
2.20.1