[igt-dev] [PATCH i-g-t v2] tests/gem_exec_balancer: Manually calculate VLA struct sizes

Arkadiusz Hiler
2019-06-04T13:16:00Z

VLA in structs (struct { int array[count] }) is a GCC extension, so
let's avoid using it.

v2: don't be overzealous in converting static-size structs

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Simon Ser <simon.ser@intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
---
tests/i915/gem_exec_balancer.c | 64 ++++++++++++++++++++++------------
1 file changed, 42 insertions(+), 22 deletions(-)

diff --git a/tests/i915/gem_exec_balancer.c b/tests/i915/gem_exec_balancer.c
index 33b17fc5..29438381 100644
--- a/tests/i915/gem_exec_balancer.c
+++ b/tests/i915/gem_exec_balancer.c
@@ -32,6 +32,26 @@ IGT_TEST_DESCRIPTION("Exercise in-kernel load-balancing");

#define INSTANCE_COUNT (1 << I915_PMU_SAMPLE_INSTANCE_BITS)

+static size_t sizeof_load_balance(int count)
+{
+ return offsetof(struct i915_context_engines_load_balance,
+ engines[count]);
+}
+
+static size_t sizeof_param_engines(int count)
+{
+ return offsetof(struct i915_context_param_engines,
+ engines[count]);
+}
+
+static size_t sizeof_engines_bond(int count)
+{
+ return offsetof(struct i915_context_engines_bond,
+ engines[count]);
+}
+
+#define alloca0(sz) ({ size_t sz__ = (sz); memset(alloca(sz__), 0, sz__); })
+
static bool has_class_instance(int i915, uint16_t class, uint16_t instance)
{
int fd;
@@ -93,16 +113,17 @@ static int __set_engines(int i915, uint32_t ctx,
const struct i915_engine_class_instance *ci,
unsigned int count)
{
- I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, count);
+ struct i915_context_param_engines *engines =
+ alloca0(sizeof_param_engines(count));
struct drm_i915_gem_context_param p = {
.ctx_id = ctx,
.param = I915_CONTEXT_PARAM_ENGINES,
- .size = sizeof(engines),
- .value = to_user_pointer(&engines)
+ .size = sizeof_param_engines(count),
+ .value = to_user_pointer(engines)
};

- engines.extensions = 0;
- memcpy(engines.engines, ci, sizeof(engines.engines));
+ engines->extensions = 0;
+ memcpy(engines->engines, ci, sizeof(engines->engines));

return __gem_context_set_param(i915, &p);
}
@@ -119,30 +140,30 @@ static int __set_load_balancer(int i915, uint32_t ctx,
unsigned int count,
void *ext)
{
- I915_DEFINE_CONTEXT_ENGINES_LOAD_BALANCE(balancer, count);
- I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 1 + count);
+ struct i915_context_engines_load_balance *balancer =
+ alloca0(sizeof_load_balance(count));
+ struct i915_context_param_engines *engines =
+ alloca0(sizeof_param_engines(count + 1));
struct drm_i915_gem_context_param p = {
.ctx_id = ctx,
.param = I915_CONTEXT_PARAM_ENGINES,
- .size = sizeof(engines),
- .value = to_user_pointer(&engines)
+ .size = sizeof_param_engines(count + 1),
+ .value = to_user_pointer(engines)
};

- memset(&balancer, 0, sizeof(balancer));
- balancer.base.name = I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE;
- balancer.base.next_extension = to_user_pointer(ext);
+ balancer->base.name = I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE;
+ balancer->base.next_extension = to_user_pointer(ext);

igt_assert(count);
- balancer.num_siblings = count;
- memcpy(balancer.engines, ci, count * sizeof(*ci));
+ balancer->num_siblings = count;
+ memcpy(balancer->engines, ci, count * sizeof(*ci));

- memset(&engines, 0, sizeof(engines));
- engines.extensions = to_user_pointer(&balancer);
- engines.engines[0].engine_class =
+ engines->extensions = to_user_pointer(balancer);
+ engines->engines[0].engine_class =
I915_ENGINE_CLASS_INVALID;
- engines.engines[0].engine_instance =
+ engines->engines[0].engine_instance =
I915_ENGINE_CLASS_INVALID_NONE;
- memcpy(engines.engines + 1, ci, count * sizeof(*ci));
+ memcpy(engines->engines + 1, ci, count * sizeof(*ci));

return __gem_context_set_param(i915, &p);
}
@@ -709,15 +730,14 @@ static void indices(int i915)
continue;

for (int n = 0; n < count; n++) {
- I915_DEFINE_CONTEXT_ENGINES_LOAD_BALANCE(*balancer,
- count);
+ struct i915_context_engines_load_balance *balancer;

engines.engines[nengines].engine_class =
I915_ENGINE_CLASS_INVALID;
engines.engines[nengines].engine_instance =
I915_ENGINE_CLASS_INVALID_NONE;

- balancer = calloc(sizeof(*balancer), 1);
+ balancer = calloc(sizeof_load_balance(1), 1);
igt_assert(balancer);

balancer->base.name =
--
2.21.0