[PATCH i-g-t v3 1/5] tests/gem_ctx_exec: Fail on unsuccessful preempt timeout update

[Janusz Krzysztofik]

CI reports the following failures from basic-nohangcheck subtest:

(gem_ctx_exec:1115) CRITICAL: Test assertion failure function nohangcheck_hostile, file ../../../usr/src/igt-gpu-tools/tests/intel/gem_ctx_exec.c:374:
(gem_ctx_exec:1115) CRITICAL: Failed assertion: err == 0
(gem_ctx_exec:1115) CRITICAL: Last errno: 2, No such file or directory
(gem_ctx_exec:1115) CRITICAL: Hostile unpreemptable context was not cancelled immediately upon closure

The subtest sets 50 ms preempt timeout on each engine before proceding
with submission of spins, then it waits up to 1 second for those spins to
be terminated.  However, dump of engines' debugfs data performed by the
subtest after the failure shows preempt timeouts still at their default
values: 7500 ms on rcs0 and 640 ms on other class engines.  Dmesg records
confirm preemption timeouts triggered on other engines after 640 ms and
not on rcs0 within the 1 second limit.

As a first step, let the subtest verify return values of function calls
supposed to update the preempt timeouts with the new values.  If failed
on any engine then report that at debug level as a useful hint displayed
when the test times out on waiting for spin termination.

v2: No changes.
v3: Don't fail on unsuccessful update of preempt_timeout_ms, older
    platforms don't support it but can still succeed.

Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/6268
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
---
 tests/intel/gem_ctx_exec.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/tests/intel/gem_ctx_exec.c b/tests/intel/gem_ctx_exec.c
index d6aa8ba0aa..f3e252d10e 100644
--- a/tests/intel/gem_ctx_exec.c
+++ b/tests/intel/gem_ctx_exec.c
@@ -308,8 +308,7 @@ static void nohangcheck_hostile(int i915)
 	igt_hang_t hang;
 	int fence = -1;
 	const intel_ctx_t *ctx;
-	int err = 0;
-	int dir;
+	int dir, err;
 	uint64_t ahnd;
 
 	/*
@@ -333,8 +332,11 @@ static void nohangcheck_hostile(int i915)
 		int new;
 
 		/* Set a fast hang detection for a dead context */
-		gem_engine_property_printf(i915, e->name,
-					   "preempt_timeout_ms", "%d", 50);
+		err = gem_engine_property_printf(i915, e->name,
+						 "preempt_timeout_ms", "%d", 50);
+		igt_debug_on_f(err < 0,
+			       "%s preempt_timeout_ms update failed: %d\n",
+			       e->name, err);
 
 		spin = __igt_spin_new(i915,
 				      .ahnd = ahnd,
@@ -362,6 +364,7 @@ static void nohangcheck_hostile(int i915)
 	intel_ctx_destroy(i915, ctx);
 	igt_assert(fence != -1);
 
+	err = 0;
 	if (sync_fence_wait(fence, MSEC_PER_SEC)) { /* 640ms preempt-timeout */
 		igt_debugfs_dump(i915, "i915_engine_info");
 		err = -ETIME;
-- 
2.45.2